Question

Use substitution to solve the linear system of equations. {x = 4 -y = 1/2 x

Answer 1

Interpreting the system as
x = 4 − y
y = (1/2)x

substitute y = (1/2)x into x = 4 − y:
x = 4 − (1/2)x
Multiply by 2: 2x = 8 − x
3x = 8
x = 8/3

Then y = (1/2)x = (1/2)(8/3) = 4/3.

Solution: (x, y) = (8/3, 4/3).

(If you instead meant x = 4 − y = (1/2)x as a chain equality, that gives x = 0, y = 4.)