Question

What is the solution to the system of equation?
y= 1.5x - 4
y= -x

Answer 1

y= 1.5x - 4
y= -x

replace y= -x into y= 1.5x - 4

y= 1.5x - 4
-x = 1.5x - 4

1.5x +x = 4
2.5x = 4
x = 1.6

y= -x
y = -1.6

answer: (1.6, -1.6) is the solution

Answer 2

we can solve this by using substitution method:

instead of y put -x in the first equation:

y = 1.5x - 4 => -x = 1.5x - 4
-x + x = 1.5x - 4 + x
0 = 2.5x - 4
0 + 4 = 2.5x - 4 + 4
2.5x = 4
x = 4/2.5
x = 1.6 and y = -1.6