Question 1147542
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Fine until the last step....<br>
0.02X - 0.05X = 450 - 630 (okay)
0.03X = -180 (not okay)<br>
0.02X-0.05X = -0.03X, not 0.03X<br>
Out of carelessness, or whatever else, it is easier to make mistakes working with negative numbers than with positive numbers.  So I would do things a bit differently earlier in your work:<br>
630+0.02X /(9000+X) = 0.05
630 +0.02X = 0.05(9000 + X)
630+0.02X = 0.05(9000) + 0.05 (X)
630 + 0.02X = 450+0.05X<br>
At this point, your next step was
0.02X-0.05X = 450-630<br>
I would move terms differently so that the "X" term is positive:<br>
630-450 = 0.05X-0.02X
180 = 0.03X
...<br>