Let's make a diagram to visualize the problem.
Let's find the distance covered by car A using the formula d = v*t.
[tex]d_A=v\cdot t=40\cdot\frac{mi}{h}\cdot5h=200mi[/tex]Car A covered 200 miles.
Subtract to obtain the distance covered by car B.
[tex]d_B=375mi-200mi=175mi[/tex]Then, we use the formula v = d/t to find the speed of car B.
[tex]\begin{gathered} v_B=\frac{d_B}{t}=\frac{175mi}{5h} \\ v_B=35\text{mph} \end{gathered}[/tex]