On roller-skates, Ian can travel 3/4 of a mile in 5 minutes. On his bike, he can travel 3 1/2 miles in 12 minutes. How fast, in miles per hour, can Ian travel on roller skates and on his bike?

Roller skates speed = 9 miles per hour

Bike speed = 17.5 miles per hour

Step-by-step explanation:

On roller-skates, Ian can travel 3/4 of a mile in 5 minutes.

Speed = Distance(miles)/Time(hours)

Convert 5 minutes to hour

60 minutes = 1 hour

5 minutes = 5/60

= 1/12 hour

Hence, his speed =

3/4mile ÷ 1/12

= 3/4 × 12/1

= 9 miles per hour

On his bike, he can travel 3 1/2 miles in 12 minutes.

Convert 12 minutes to hour

60 minutes = 1 hour

12 minutes = 12/60 = 1/5

Hence, his speed =

3 1/2 mile ÷ 1/5

= 7/2 ÷ 1/5

= 7/2 × 5/1

= 35/2 miles per hour

= 17.5 miles per hour