Explanation:
(8) We need to find the expression that is equivalent to 15x + 8y.
Option (A) :
![5(3x+y)-3y=15x+5y-3y=15x+2y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f55ob50clizct3mn91a4151vx7w7bc9wam.png)
Option (B) :
![15x-2y-10](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xnqjslp3wjuryab21t40etyjnc2sdl8b1i.png)
Option (C)
![3(5x+2y)+2y=15x+6y+2y=15x+8y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/j3jgf9aobq8bz4oh8gbhgqqysft2scbev0.png)
Option (D)
![10(x+y)+5y-2x=8x+15y](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ouvb058xkip3a12euw1lvty7cvqydeninf.png)
So, the correct option is (c).
(9) We need to solve the following equation for q.
![p(q+r)=1](https://img.qammunity.org/2020/formulas/mathematics/middle-school/m0smvnvvu1978n5urns798bzqeylj2uitk.png)
Dividing both sides of the above equation by (q+r) as :
![p=(1)/((p+r))](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qfsjkmvzbtymgqdw1sj3seg4b1ywz65bw0.png)
Hence, this is the required solution.