On a particular day, the wind added 5 miles per hour to alfonso's rate when he was cycling with the wind and subtracted 5 miles per hour from his rate on his return trip. alfonso found that in the same amount of time he could cycle 75 miles with the wind, he could go only 45 miles against the wind. what is his normal bicycling speed with no wind?

  20 mph

Step-by-step explanation:

The ratio of Alfonso's speed with the wind to his speed against the wind is ...

  (x +5)/(x -5) = 75/45 . . . . where x is his speed with no wind

Multiplying by 3(x-5), we get ...

  3(x +5) = 5(x -5)

  40 = 2x . . . . eliminate parentheses, add 25-3x

  20 = x . . . . . divide by 2

Alfonso's speed with no wind is 20 miles per hour.

0lz try yourself sorry for not answering