If you have 40 cups of milk how many quarts do you have?

1 quart = 4 cups. In order to solve your problem, you can cross multiply:

1/4 = x/40  multiply 1 and 40, and then multiply "x" and 4:

40 = 4x  now, you must isolate the "x." To do so, use the opposite operation in which the "x" is involved in. Here we have 4x (the x is multiplied to the 4) so we must divide 4 from 4x. This cancels the 4 and leaves us with just "x".

What you do to one side, you must do to the other. So you also divide 40 by 4, which is 10. 

10 = x, therefore, there are 10 quarts in 40 cups. 

40 divide 4 equal 10,so 40cup of milk equal 10quarts