# Question #254f8

Oct 7, 2017

28 laps

#### Explanation:

Let Jackie's laps = J, and Ronnie's = R.

Now turn the info you're given into equations:

$2 J = 3 R$ (for every three laps of J, R swims 2)

$J + R = 70$ (total laps = 70)
$R = 70 - J$ (rearranging)

$2 J = 3 \left(70 - J\right)$ (getting rid of a variable - plugging in what R's equal to)

$2 J = 210 - 3 J$
$5 J = 210$
$J = 42$

Now put this back into the first equation to find $R$:
$42 + R = 70$
$\therefore R = 28$

So Ronnie swam 28 laps.