Solving Systems of Equations by Substitution · Exercise 53

Stephanie left Riverside, California, driving her motorhome north on Interstate 15 towards Salt Lake City at a speed of 56 miles per hour. Half an hour later, Tina left Riverside in her car on the same route as Stephanie, driving 70 miles per hour. Solve the system $\{\begin{array}{l}56s=70t\\ s=t+\frac{1}{2}\end{array}$.

ⓐ for $t$ to find out how long it will take Tina to catch up to Stephanie.
ⓑ what is the value of $s$, the number of hours Stephanie will have driven before Tina catches up to her?

OpenStax, Elementary Algebra 2e · §5.2 Solving Systems of Equations by Substitution · Exercise 53