Solve by substitution:

Question

x + 2y =1
8x + 8y =4

Answer 1

x + 2y =1 --- (1)
8x + 8y =4 --- (2)

From (1),
x + 2y = 1
x = 1 - 2y --- (3)

Sub (3) into (2),
8 (1-2y) + 8y = 4
8 - 16y + 8y = 4
-8y = 4 - 8
-8y = -4
y = -0.5

sub y = -0.5 into (3),
x = 1 - 2(-0.5)
x = 1 + 1
x = 2

CHECK: sub x = 2 and y = -0.5 into (1),
2 + 2(-0.5) = 1