y = x + 7 & y = 8x + 21

Question

Solve the system of equations



Answer 1

Since you have x+7 AND 8x +21 BOTH = y, then x+7 = 8x+21

i.e., If Sally is as tall and Jeff, and Tim is as tall as Jeff, then Sally is as tall as Tim.

Answer 2

y = x + 7

y = 8x + 21

8x + 21 = x + 7

7x = -14

x = -2