One tank s filling at a rate of 3/4 gallon per 2/3 minute . a second tank is filling at a rate of 5/8 gallon per 1/2 minute. which tank is filling faster ?

This is an easy question. All required information's are provided in the question. In the first case it is given that the tank is getting filled at a rate of 3/4 gallon per 2/3 minute. So by getting the speed of filling we can compare this withe the speed at which the second tank is getting filled. The second tank fills at a rate of 5/8 gallon in 1/2 minute.
If we take the case of the first tank, then,
Speed of filling the first tank = (3/4) * (3/2)
                                              = 9/8
So the first tank is filled at the rate of 9/8 gallons per minute.
Now if we take the case of the second tank, then,
Speed of filling the second tank = (5/8) * 2
                                                   = 10/8
So the second tank fills at the rate of 10/8 gallons per minute.
Now we can say that the second tank is getting filled at a faster rate.