Question

What is the value of x and what is the value of y in these equations (x in both has to be the same number, likewise for y)?

x+y=7
3x+y=45

Thanks!

Answer 1

To answer this, you should "subtract" x+y=7 from 3x+y=45.

What is left is 2x=38, where x then equals 19.

Plug this value into any of the equations (I will choose x+y=7 for simplicity).

19+y=7, y=-12

Check this answer by plugging it into the other equation.
3(19) + (-12) =45
45=45 so it is correct

X=19 and Y=-12