Mathematics

Nick Schwartz

13 August, 10:50

Devon's teacher requires that students show each step in solving a problem. Devon wrote the following when solving the equation x - 7 = 20:

x - 7 = 20

x - 7 = 20 + 7

x = 27

The teacher said that Devon's work was not shown correctly. Why?

A) Devon's final answer should be 13

B) Devon should have shown that he added 7 to both sides

C) Devon should have shown that he subtracted 7 from both sides

D) Devon should have shown that he added 7 to the left side only