Mark had some stickers. He gave ²₃ of his stickers to Jenson and bought 4 new stickers. After that, he gave ²₅ of his remaining stickers to his sister and bought another 7 new stickers. In the end, Mark had 40 stickers.

1. How many stickers did Mark give to his sister?
2. How many stickers did Mark have at first?

(a)
Fraction of  his remaining stickers after he gave to his sister
= 1 - ²₅
= ³₅

³₅ of his remaining stickers = 40 - 7 = 33
¹₅ of his remaining stickers = 33 ÷ 3 = 11
²₅ of his remaining stickers = 2 x 11 = 22

Number of stickers that Mark gave to his sister = 22

(b)
⁵₅ of his remaining stickers = 5 x 11 = 55

Fraction of his total stickers after he gave to Jenson
= 1 - ²₃
= ¹₃

¹₃ of his total stickers = 55 - 4 = 51
³₃ of his total stickers = 3 x 51 = 153

Number of stickers that Mark had at first = 153 

Answer(s): (a) 22; (b) 153