Brian saved 4/5 of his paycheck and spent 1/2 of the remaining money. He was then left with $3. What was the original value of Brian's paycheck?
The amount that Brian spent is 1/10 of his total paycheck, so we know that 1/10 of the paycheck is 3 dollars, since he spent only half of the remaining money. Therefore, if m is the total money he has, 1/10*m=3, so m is 30 dollars.