Shiyun had some marbles at first. She gave 25 of her marbles to her sister and 14 of her marbles to her friend. After that, her mother gave her another 20 marbles. She had 111 marbles in the end. How many marbles did Shiyun have at first?
Fraction of marbles left after giving to her sister and her friend
= 1 -
25 -
14 = 1 -
820 -
520 = 1 -
1320 =
720 Number of marbles left after giving to her sister and her friend = 7 u
Number of marbles left after her mother gave her another 20 marbles = 7 u + 20
7 u + 20 = 111
7 u = 111 - 20
7 u = 91
1 u = 91 ÷ 7 = 13
Number of marbles that Shiyun had at first
= 20 u
= 20 x 13
= 260
Answer(s): 260
