Question

Nisha did the work below to solve an equation.

Step 1 7 b + 3.2 b minus 5 = 18.92
Step 2 10.2 b minus 5 = 18.92
Step 3 5.2 b = 18.92
Step 4 b = 3.64

In which step did Nisha make her first error?
Step 1
Step 2
Step 3
Step 4

Answer 1

Step 3.

Reason: 7b + 3.2b = 10.2b is correct (Step 2). From 10.2b − 5 = 18.92 you must add 5 to both sides: 10.2b = 23.92, not 5.2b = 18.92. (So Step 3 is the first error.) The correct solution gives b = 23.92/10.2 ≈ 2.3451.