Paul had some marbles he gave 20 to Yongjun

Question

Paul had some marbles he gave 20 to Yongjun and 1/4 of the rest to fauzi he then had 1/2 of the number of marbles he had at first. How many marbles did paul have at first?

Answer 1

m- 20 - (1/4)(m-20) = (1/2)m

 

m - 20 - m/4 + 5 = m/2

 

m - m/4 - m/2 = 20 - 5

 

m/4 = 15

 

m = 60 marbles

 

Check:  60 - 20 = 40

            40 - 10 = 30

            30 is half of 60