B =60×3÷(7+3)= 18 people;

2. If sugar is X yuan per box and cake is Y yuan per box, then there will be;

8x+5y= 17 1( 1)

5x+2y=90(2)

( 1)×2-(2)×5:

16x-25x = 342-450；

-9x=- 108

x = 12；

Bring in (1):

96+5y = 17 1；

5y = 75

y = 15；

So sugar is 12 yuan per box, and cake is 15 yuan per box.

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