# math 12

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Ryan reaches into his gym bag for a pair of running shoes. If there are seven different pairs of shoes loose in the bag, how many ways can he pick two shoes that do not match?

• combinations -

Number of ways he can choose two shoes
=14C2
=14!/(2!12!)
=14*13/2
=91
Number of ways he can choose matching shoes
= 7
So how many ways can he choose non-matching shoes?

• math 12 -

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