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
x = postcard 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 Ask Algebra House Comments are closed.

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