英數(暑期作業)

7.y is 9/25 of x.what percentage of x is y?

9/25 X 100% = 36%

8.3/8 of all the butter cookies have been eaten.what percentage of the cookies is now left?

(1-3/8) X 100% = 62.5%
9.In abakery,250 cakes and 400 bread were sold yesterday.the number of cakes sold today is decreased by 10% and that of bread is increased by 15%.find the total number of cakes and bread sold today.

250 X (1-10%) + 400 X (1+15%)
=250 X 90% + 400 X 150%
=250 X 0.9 + 400 X 1.5
=225 + 600
=825