The solution of the system is (-5, 2) means
x = -5
y = 2
The form of the linear equation is y = m x + b
Let m = 1 and substitute x by -5 and y by 2 to find b
∵ 2 = 1(-5) + b
∴ 2 = -5 + b
→ Add 5 to both sides
∵ 2 + 5 = -5 + 5 + b
∴ 7 = b
∴ y = x + 7 ===== (1)
Let m = 2 and substitute x by -5 and y by 2
∵ 2 = 2(-5) + b
∴ 2 = -10 + b
→ Add 10 to both sides
∵ 2 + 10 = -10 + 10 + b
∴ 12 = b
∴ y = 2x + 12 ===== (2)
The system of equations is
y = x + 7 and y = 2x + 12