Question

what is the solution of the following system?
4x-y=15
3x+2y=-8

(-1,-19)
(2,-7) <--- is this the right answer?
(4,-5)
(5,5)

Answer 1

So your system is
\[4x-y=15\]
\[3x+2y=-8\]
scaling the first one up by 2, allows you to cancel out the y terms leaving you with
\[11x=22\]
So, x=2...which only is true in one of the choices...the one you picked :)

Answer 2

4x - y = 15 --->(2)
3x + 2y = -8
--------------
8x - 2y = 30 (result of multiplying by 2)
3x + 2y = -8
--------------add
11x = 22
x = 2
now sub 2 in for x in either equation to find y
4x - y = 15
4(2) - y = 15
8 - y = 15
8 - 15 = y
- 7 = y

x = 2 and y = -7......you are correct