Algebra · real student question

Solve for x: 0.58333x + 916.9998 = 0.72727x + 965.9089.

Question

Solve for xx:

0.58333x+916.9998=0.72727x+965.90890.58333x+916.9998=0.72727x+965.9089

Step-by-step solution

  1. Recognise the decimals for what they are. 0.583337120.58333\approx\tfrac{7}{12} and 0.727278110.72727\approx\tfrac{8}{11} are rounded fractions, so the data carry five-decimal precision at best. Work with the given decimals but do not claim more than about five significant figures in the answer.

  2. Gather the xx terms on the larger-coefficient side. Subtract 0.58333x0.58333x from both sides:

    916.9998=(0.727270.58333)x+965.9089=0.14394x+965.9089916.9998=(0.72727-0.58333)x+965.9089=0.14394x+965.9089

  3. Gather the constants.

    916.9998965.9089=48.9091916.9998-965.9089=-48.9091

    giving

    48.9091=0.14394x-48.9091=0.14394x

  4. Divide, keeping the intermediate digits.

    x=48.90910.14394=339.78810339.79x=\frac{-48.9091}{0.14394}=-339.78810\ldots\approx -339.79

    Because 1/0.143946.951/0.14394\approx 6.95, the answer is roughly seven times the constant gap; truncating that quotient at 339.78-339.78 loses the correct rounding.

  5. Verify by evaluating both sides. Left: 0.58333(339.7881)+916.9998=718.800.58333(-339.7881)+916.9998=718.80. Right: 0.72727(339.7881)+965.9089=718.800.72727(-339.7881)+965.9089=718.80. They match, so x339.79x\approx-339.79 is correct.

Answer

x339.79x\approx -339.79

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