Shiyun had some erasers at first. She gave 19 of her erasers to her cousin and 16 of her erasers to her friend. After that, her mother gave her another 12 erasers. She had 77 erasers in the end. How many erasers did Shiyun have at first?
Fraction of erasers left after giving to her cousin and her friend
= 1 -
19 -
16 = 1 -
218 -
318 = 1 -
518 =
1318 Number of erasers left after giving to her cousin and her friend = 13 u
Number of erasers left after her mother gave her another 12 erasers = 13 u + 12
13 u + 12 = 77
13 u = 77 - 12
13 u = 65
1 u = 65 ÷ 13 = 5
Number of erasers that Shiyun had at first
= 18 u
= 18 x 5
= 90
Answer(s): 90
