Kathy made 396 more pandan wafers than banana wafers. After she gave away ⁵₇ of the pandan wafers and ¹₈ of the banana wafers, there were an equal number of pandan wafers and banana wafers left. How many pandan wafers did she give away?

	Pandan wafers	Banana wafers	Difference
Before	7x7 = 49 u	8x2 = 16 u	33 u
Change	- 5x7 = - 35 u	- 1x2 = - 2 u
After	2x7 = 14 u	7x2 = 14 u

Fraction of pandan wafers left
= 1 - ⁵₇
= ²₇

Fraction of banana wafers left
= 1 - ¹₈
= ⁷₈

The number of pandan wafers and banana wafers in the end is the same. Make the numerators the same.  LCM of 7 and 2 is 14.

²₇ of pandan wafers = ⁷₈ of banana wafers
¹⁴₄₉ of pandan wafers = ¹⁴₁₆ of banana wafers

Number of more pandan wafers than banana wafers at first
= 49 u - 16 u
= 33 u

33 u = 396

1 u = 396 ÷ 33 = 12

Number of pandan wafers that Kathy gave away
= 49 u - 14 u
= 35 u
= 35 x 12
= 420

Answer(s): 420