STEP - BY - STEP EXPLANATION
What to find?
The number each instructor teach per week.
Given:
Total number they teach per week =39
let e = number of classes Erica teaches per week and b = the number of classes Bo teaches per week.
e =2b - 15
Step 1
Form the linear equation.
[tex]b+e=39[/tex]
Step 2
Substitute e=2b-15 into the above.
[tex]b+2b-15=39[/tex]
Step 3
Collect like term.
[tex]b+2b=39+15[/tex][tex]3b=54[/tex]
Step 4
Divide both-side of the equation by 3.
[tex]\frac{3b}{3}=\frac{54}{3}[/tex][tex]b=18[/tex]
Step 5
Determine Erica's age.
[tex]\begin{gathered} b+e=39 \\ \\ e=39-b \\ \\ e=39-18 \\ \\ e=21 \end{gathered}[/tex]
ANSWER
c. 18 Bo; 21 Erica
