Justine swims freestyle at a pace of 150 laps per hour.Justine swims breaststroke 20 laps per hour slower than she swims butterf

Answer: her breaststroke speed is 30 laps per hour.

Step-by-step explanation:

Let b represent Justine’s butterfly speed.

Let r represent Justine’s breaststroke speed.

Justine swims freestyle at a pace of 150 laps per hour. If Justine’s freestyle speed is three times faster than her butterfly speed, it means that

3b = 150

b = 150/3

b = 50 laps per hour

Justine swims breaststroke 20 laps per hour slower than she swims butterfly. This means that

r = b - 20

r = 50 - 20

r = 30 laps per hour