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?
a. Step 1
b. Step 2
c. Step 3
d. Step 4