Let x = price of a tuna sandwich
Let y = price of a turkey sandwich
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(1) 6x + 6y = 30
(2) 4x + 8y = 30.6
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(1) x + y = 5
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(2) 40x + 80y = 306
(2) 20x + 40y = 153
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Multiply both sides of (1) by 20
and subtract (1) from (2)
(2) 20x + 40y = 153
(1) -20x - 20y = -100
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20y = 53
y = 2.65
and
(1) x + y = 5
(1) x + 2.65 = 5
(1) x = 2.35
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A tuna sandwich costs $2.35
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