You have 16 stamps. Some are postcard stamps that cost $0.23, and the rest cost $0.41. If you spend a total of $5.30 on the stamps, how many postcard stamps do you have?

A.) 7

B.) 8

C.) 9

D.) 10

E.) cannot be determined

A.) 7

B.) 8

C.) 9

D.) 10

E.) cannot be determined

**x = postcard stamps**

y = other stamps

y = other stamps

x + y = 16 {you have 16 total stamps}

0.23x + 0.41y = 5.3 {postcard stamps are $0.23 and others are $0.41}

-0.23x - 0.23y = -3.68 {multiplied top equation by -0.23}

0.23x + 0.41y = 5.3 {bottom equation stays the same}

---------------------------

0.18y = 1.62 {added the two equations}

y = 9 {divided each side by 0.18}

x + y = 16 {top original equation}

x + 9 = 16 {substituted 9, in for y, into top original equation}

x = 7 {subtracted 9 from each side}

**A.) 7 postcard stamps**

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