Question

Bob sells hats and scarves.

At the start of the day, he has : hats : scarves = 4 : 3
During the day he sells 25 hats.
At the end of the day, he has: hats : scarves = 7 : 9

How many scarves does Bob have in his store

Answer 1

We define variables:
 x: number of hats
 y: number of scarves
 We have the following equations:
 x / y = 4/3
 x-25 / y = 7/9
 Solving the system of equations we have
 x = 60
 y = 45
 Answer:
 Bob has 45 scarves in his store