First lets put these numbers into improper fractions. 4 2/5 becomes 22/5 becomes we multiple the 4 by the denominator,5, and add to the dividend.
We do the same process with 16 1/2 and get 33/2.
We then need to set these equations so that they have the same base. In these case a common factor is 10.
We multiple our first equation by 2 and get 44/10, and then we multiple our second equation by 5 and get 165/10.
We then setup the equation (44/10)*x=165/10
We can multiple each side out by 10, leaving us 44x=165
Divide each side by 44, which leaves us with x=165/4
When you simiplify the problem we are left with x and our answer.
When done correctly you will find that it takes 3 3/4 minutes to fill a tank that holds 16 1/2 gallons.