Question: Find the answer to the math problem: Dean has 30 marbles. He gives 1/5  of them to Jamie and gives 10 to Donald. How many marbles are left for Dean?
Answer: 
Dean gives 30 x 1/5 = 6 marbles to Jamie.
He gives a total of 6 + 10 = 16 marbles in all.
So, Dean has 30 - 16 = 14 marbles left.