gunakan metode substitusi

a)
4x-y=5
4x = 5+y
4x-5 = y atau y = 4x-5

x-3y = -7
x-3(4x-5) = -7
x-12x + 15 = -7
-11x = -7-15
-11x = -22
x = -22/-11
x = 2

4x-y=5
4(2)-y=5
8-y=5
-y=5-8
-y=-3
y=3