QUESTION 1
The given system of equation is
![y=x-6...eqn1](https://img.qammunity.org/2019/formulas/mathematics/high-school/sryenu49r36pcklrrnshwvl8t47zul34h7.png)
and
![3x+2y=8...eqn2](https://img.qammunity.org/2019/formulas/mathematics/high-school/7n783fj0mtjylh7psn1x0hzv9cgsg269fv.png)
Let us substitute equation (1) into equation (2) to get,
![3x+2(x-6)=8](https://img.qammunity.org/2019/formulas/mathematics/high-school/ha90lzjqywd1co09urjjmltx5zefmxqmpb.png)
We expand the bracket to get,
![3x+2x-12=8](https://img.qammunity.org/2019/formulas/mathematics/high-school/zsjt3bavxve6csnkqte6vdghh1uwrzpy3e.png)
We simplify to get.
![5x-12=8](https://img.qammunity.org/2019/formulas/mathematics/high-school/hjfhpcwflcojmyg3jndglg1axhqneaerb3.png)
We group like terms to get
![5x=8+12](https://img.qammunity.org/2019/formulas/mathematics/high-school/uapqrxe9f6r2hfyfbxy24n5r9xiw9vgnlu.png)
![\Rightarrow 5x=20](https://img.qammunity.org/2019/formulas/mathematics/high-school/5gsebhby2d1a52qqdckbrhjnou24zlxbdr.png)
![\Rightarrow x=4](https://img.qammunity.org/2019/formulas/mathematics/middle-school/zv0kzlgw1z4nhngowi7wx50sg74hkvg790.png)
We now substitute
in to equation (1) to obtain,
![y=4-6=-2](https://img.qammunity.org/2019/formulas/mathematics/high-school/8c93c00yu7dtphekso3kbsqn99e1pjiyqn.png)
The correct answer is option A.
QUESTION 2
The given system of equations is
![y-x=9...eqn1](https://img.qammunity.org/2019/formulas/mathematics/high-school/4w54p3drb2tvjth0i2chr2srd5pcfjjc7i.png)
and
![10+2x=-2y...eqn2](https://img.qammunity.org/2019/formulas/mathematics/high-school/uj7olbfq7z5vm8iqswbqhbgsbps8f0n6cy.png)
We make y the subject in equation (2) to get,
![y=-x-5..eqn3](https://img.qammunity.org/2019/formulas/mathematics/high-school/2jm7wr9yeqku1fsfbcni825g4lnrpkg5ej.png)
We put equation (3) into equation (1) to obtain,
![-x-5-x=9](https://img.qammunity.org/2019/formulas/mathematics/high-school/jt0v7up443x0nmepn5puha4x3rgwi2tviq.png)
We group like terms to get,
![-x-x=9+5](https://img.qammunity.org/2019/formulas/mathematics/high-school/it1elbidzw1jrrwwc8jpk9zssty6lwni29.png)
This implies that,
![-2x=14](https://img.qammunity.org/2019/formulas/mathematics/high-school/icoinsuhsf0rrsyz6yh79wkcl5p56vjr85.png)
We divide through by
to get,
![x=-7](https://img.qammunity.org/2019/formulas/mathematics/middle-school/gah7jbzapabclh3hbypv4zu4w4ehc4qd5o.png)
Hence the x-coordinate is
![-7](https://img.qammunity.org/2019/formulas/mathematics/middle-school/62dg37166tk2nxorf7si5eef2mmg208qzw.png)
QUESTION 3
The given system is
![y=3x-1..eqn1](https://img.qammunity.org/2019/formulas/mathematics/high-school/n9ha8klwx3t2on60kkjq0301yafis1vcxz.png)
and
![x-y=-9...eqn2](https://img.qammunity.org/2019/formulas/mathematics/high-school/56uvprjgd0dzx2w4qlf2px6i4usowxgdlf.png)
We make
the subject in equation (2) to get,
![x=y-9...eqn3](https://img.qammunity.org/2019/formulas/mathematics/high-school/enxux5x88n0bovvz7sjk45tpgrlwwy3vhs.png)
We put equation (3) into equation (1) to obtain,
![y=3(y-9)-1](https://img.qammunity.org/2019/formulas/mathematics/high-school/zw1n8zphucyfqglaas58a1fwg7e4b0cd3y.png)
We expand the bracket to get,
![y=3y-27-1](https://img.qammunity.org/2019/formulas/mathematics/high-school/iqnpa2ffsd44chdhiv8slx7gye5votpmv4.png)
Group like terms to get,
![y-3y=-27-1](https://img.qammunity.org/2019/formulas/mathematics/high-school/7aqxikja9b4hydgw4fgwjogazhlj9aj5g6.png)
We simplify to get;
![-2y=-28](https://img.qammunity.org/2019/formulas/mathematics/high-school/m9q38ziovfy3avyxcbm2gfjxmwp08zdcjh.png)
This implies that,
![y=14](https://img.qammunity.org/2019/formulas/mathematics/high-school/z1d2mvq5jtgfpw7ni11s479fcbdlsokj8m.png)
Therefore the y-coordinate is 14.