Erika has some chocolate bars and mochi balls. If she packs a chocolate bar and a mochi ball in each bag, there will be 25 mochi balls left. If she packs 3 chocolate bars and 4 mochi balls in each bag, there will be 27 chocolate bars left. How many chocolate bars and mochi balls does she have in all?

	Case 1		Case 2
	Chocolate Bars	Mochi Balls	Chocolate Bars	Mochi Balls
Before	1 u	1 u + 25	3 p + 27	4 p
Change	- 1 u	- 1 u	- 3 p	- 4 p
After	0	25	27	0

The number of chocolate bars at first is the same for Case 1 and 2.
The number of mochi balls at first is also the same for Case 1 and 2.

1 u = 3 p + 27 --- (1)

1 u + 25 = 4 p
1 u = 4 p - 25 --- (2)

(2) = (1)
4 p - 25 = 3 p + 27
4 p - 3 p = 27 + 25

1 p = 52

Total number of chocolate bars and mochi balls
= (3 p + 27) + 4 p
= 7 p + 27
= 7 x 52 + 27
= 364 + 27
= 391

Answer(s): 391