Problem 1 

a) the cakes that 15 children have:

15×3=45(cakes)

The packets of cakes they need to buy:

45÷6=7,5

So they  need to buy 8 packets of cake

b)the small bag of sweets that 15 children have:

15×1=15( small bag of sweets)

The packets of sweets they need to buy:

15÷5=3(packets of sweets)

The packets of cakes cost:

8×2,99=23,92($)

c)They will spend:

23,92+2,89=26,81($)

d)The change she received:

40-26,81=13,19($)

Problem 2

a)the pencils that 34 children have:

34×2=68(pencils)

The packs he need to buy:

68÷6=11,33

So he need to buy 12 packs and have 4 pencils left over (6×12-68=4)

b)the 12 packs have costs:

12×1,99=23,88($)

The change he received:

30-23,88=6,12($)