The distance between two piers on a river is 45 miles. It takes a motorboat, moving downriver, 2 hr 15 min to complete the journey. How much time does it take the same boat to go back upstream if the current flows at 2.5 mph?

3 hours

Step-by-step explanation: we can make a variable for our answer(x)

Now, we need to find the speed of the boat without the current (y)

we can make this equation: d/t = s: 45/(y + 2.5) = 2 1/4

hence: y = 17.5

now we can substitute in the current's speed: y -2.5

17.5 - 2.5 is 15

now we can solve for x

45/15 = 3

hence, we get 3 hours as our answer

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step-by-step explanation:

let m = monomial

let t = trinomial

so, m times t = t.

monomial times a trinomial = another trinomial.