math
posted by Anonymous on .
A boat travels down the river in 2.6 hours. The return trip up river takes 3.9 hours. A one way trip down or up river is a distance of 21 miles. If the boat is traveling at maximum speed, what is the boats speed measured in waters with no current? You need to use systems to solve this problem. Round your speed to the tenth of a mile per hour. You do not need to include units as the problem requires a value in miles per hour.

since distance = time*speed, if the boat=b and the river=r mph,
2.6(b+r) = 21
3.9(br) = 21
b = 175/26 = 6.73 mph
r = 25/36 = 1.53 mph