Fangfang and Yuanyuan have 70 books. If Fangfang gives Yuanyuan five books, Yuanyuan will have four more books. How many books do they each have?
Suppose a square has x shares and a circle has 70-x shares.
[(70-x)+5]-(x-5) = 4
70-x+5-x+5 = 4
2x = 76
x=38
70 x = 32
Fangfang has 38 original books and Yuanyuan has 32 original books.