x = -1
y = 7
Step-by-step explanation:
2y - 4x = 18 ...equation 1
18 = 3x+3y ...equation 2
Using substitution method:
We make y the subject of formula in equation 1:
2y - 4x = 18
2y = 18 + 4x
y = 1/2(18 + 4x)
y = 9 + 2x
substitute for y in equation 2:
18 = 3x + 3(9 + 2x)
18 = 3x + 27 + 6x
18 = 9x + 27
18 -27 = 9x
-9 = 9x
divide both sides by 9:
-9/9 = 9x/9
-1 = x
x = -1
substitute for x in equation 1:
2y - 4(-1) = 18
2y + 4 = 18
2y = 18-4
2y = 14
y = 14/2
y = 7