For a school trip. Maria decides to order T-shirts for everyone. It costs $4 for a medium size, and $5 for a large size. She orders a total of 70 shirts and spends a total of $320. How many are medium shirts?
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For a school trip. Maria decides to order T-shirts for everyone. It costs $4 for a medium size, and $5 for a large size. She orders a total of 70 shirts and spends a total of $320. How many are medium shirts?
L + M = 70 multiply both sides by 5 —> 5L + 5M = 350
5L + 4M = 320 —> 5L + 4M = 320
subtract to obtain —> M = 30
and since L + M = 70 —> L = 40
check answer
Does (5)(40) + (4)(30) = 320 ?
200 + 120 = 320 ?
320 = 320 True
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