A common multiple is a number that is a multiple of two or more numbers.
Take 10 for example. It is a multiple of 5 and 2.
It's basically asking 75% of what number is 63 so x * 75% = 63
75% in decimal form is .75
divide 63 by .75 which is 84.
so 75% of 84 would be 63.
Wouldn't it be divided, I'm pretty sure it would be, if not I'm sorry