Question

A motorboat travels 9 miles downstream (with the current) in 30 minutes. The return trip upstream (against the wind) takes 90 minutes. Which system of equations can be used to find x, the speed of the boat in miles per hour, and y, the speed of the current in miles per hour? Recall the formula d = rt.

Answer 1

x=12 mile/hour(the speed of the boat)

y=6 mile/hour(the speed of the current)

Explanation:

According to the Question,

let, x be the speed of the boat in miles per hour and y be the speed of the current in miles per hour.

• Given That, A motorboat travels 9 miles downstream (with the current) in 30 minutes. Thus, x+y = 0.3 mile/minute ⇒ 0.3×60 ⇒ 18mile/hour

x+y=18 ---- Equation 1

• & The return trip upstream (against the wind) takes 90 minutes. Thus, x-y = 0.1 mile/minute ⇒ 0.1×60 ⇒ 6mile/hour

x-y=6 ---- Equation 2

On Adding both above Equations We get,

2x=24 ⇔ x=12 mile/hour(the speed of the boat)

& x+y=18 put Value of x=12 we get ⇔ y=6 mile/hour(the speed of the current)