Diana baked 60 cookies. ³₅ of the cookies were vanilla cookies. The rest were strawberry cookies. She gave an equal number of vanilla cookies and strawberry cookies away and had 3 times as many vanilla cookies as strawberry cookies left. How many cookies did she give away?

	Vanilla cookies	Strawberry cookies	Difference
Before	3x2 = 6 u	2x2 = 4 u	1x2 = 2 u
Change	- 3 u	- 3 u
After	3x1 = 3 u	1x1 = 1 u	2x1 = 2 u

Since Diana gave away an equal number of vanilla cookies and strawberry cookies, the difference in the number of vanilla cookies and strawberry cookies remains unchanged.  Make the difference in the vanilla cookies and strawberry cookies the same.  LCM of 1 and 2 is 2.

Total number of cookies at first
= 6 u + 4 u
= 10 u

10 u = 60

1 u = 60 ÷ 10 = 6

Number of cookies that Diana gave away
= 3 u + 3 u
= 6 u
= 6 x 6 
= 36

Answer(s): 36