Sam had some blueberry shortbreads and banana shortbreads. ⁵₇ of the number of blueberry shortbreads was equal to ¹₅ of the number of banana shortbreads. After Sam made 21 more blueberry shortbreads, the number of blueberry shortbreads was ²₅ of the number of banana shortbreads. How many shortbreads did he have altogether in the end?
Make the numerators the same. LCM of 5 and 1 is 5.

57 of blueberry shortbreads = 1x55x5 of banana shortbreads

⁵₇ of blueberry shortbreads = ⁵₂₅ of banana shortbreads

	Blueberry shortbreads	Banana shortbreads	Total
Before	7 u	25 u
Change	+ 21
After	2x5 = 10 u	5x5 = 25 u	35 u

The number of banana shortbreads remains unchanged.  Make the number of banana shortbreads the same.  LCM of 5 and 25 is 25.

Number of more blueberry shortbreads made
= 10 u - 7 u
= 3 u

3 u = 21

1 u = 21 ÷ 3 = 7

Number of shortbreads that Sam had in the end
= 10 u + 25 u
= 35 u
= 35 x 7
= 245

Answer(s): 245