Answer:
168 stickers
Step-by-step explanation:
When she gives out a fraction, there is a reduction in what she has left which is a function of what she originally had before she gave some out.
Given that Melody has 98 stickers and She gives 2/7 of them to her sister.
This means she gave her sister
= 2/7 × 98
= 28
This means she has
= 98 - 28 = 70 stickers left.
If she gave 3/5 of the remainder to her brother. Then she gave
= 3/5 × 70 = 42 stickers
This means she has
= 70 - 42 = 28 stickers left.
If she wants to increase her collection of stickers to twice what she had originally,
This means she wants to have
= 98 × 2 = 196 stickers but she has 28 stickers hence she would have to buy
196 - 28 = 168 stickers