Answer:
28 laps
Step-by-step explanation:
Let laps swam by Jackie be J, and laps swam by Ronnie be R.
"For every 3 laps that Jackie swims Ronnie swims 2 laps":
\(3R=2J\)
"they swam a combined total of 70 laps ":
\(J+R=70\)
Now, solving for J of the first equation and putting that into the 2nd equation, we can know R:
\(3R=2J\\J=\frac{3R}{2}\\and\\J+R=70\\(\frac{3R}{2})+R=70\\\frac{5}{2}R=70\\R=\frac{70}{\frac{5}{2}}=28\)
So, Ronnie swam 28 laps.
