<PRE><B>Question 511488</B>
income = 15 -2 on days worked
income = -2 on days not worked
x = days worked
y = days not worked
income = 13x -2y
income = 382
13x -2y = 382
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The other option says for the same number of days worked and not worked, so these are the same x and y, he would have earned:
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15x -3y = 438
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Set up the simultaneous equations
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13x -2y = 382
15x -3y = 438
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multiply the first by 3 and the second by 2, then subtract the second from the first
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39x -6y = 1146
30x -6y = 876
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9x +0y = 270
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x = 30
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substitute to find y
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13x -2y = 382
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13(30) -2y = 382
390 -2y = 382
-2y = -8
y = 4
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check the answers to see if these values are correct
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15(30) -3(4) = ??
450 - 12 = 438
correct
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Answer:  He worked 30 days and did not work 4 days.
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Done.</PRE>