1

Grandmother made 20 gingerbread biscuits for her grandchildren. She decorated them with raisins and nuts. First she decorated 15 cakes with raisins and then 15 cakes with nuts. At least how many cakes were decorated both with raisins and nuts?

Gerry Myerson
  • 179,216
john_121
  • 13
  • 1
    And what have you tried yourself? – Eric S. Mar 08 '16 at 11:04
  • Nothing I don't know how to proceed..Please you help me. – john_121 Mar 08 '16 at 11:08
  • 1
    You could start by just testing it yourself. Draw $20$ gingerbread biscuits. Then decorate $15$ with raisins and think of what ways you can then decorate $15$ with nuts. – Eric S. Mar 08 '16 at 11:10
  • Don't forget that you can mark an answer as accepted if it has helped you to solve your problem by clicking in the icon under the vote/downvote buttons. – S - Mar 08 '16 at 13:04

1 Answers1

1

You have $20$ cakes in total, if she decorated $15$ cakes with raisins the least possible number of cakes decorated with nuts and raisins is to decorate first the cakes that have no raisins and then decorate those that already have raisins. So the minimum number of cakes with both raisins and nuts is:

$$15 - 5 = 10$$

S -
  • 3,611
  • 2
  • 18
  • 38