Question

Five more than eight times a number is the same as twenty-one less than a number.

Equations and inequalities
ANSWERED
asked 2021-02-04
Five more than eight times a number is the same as twenty-one less than a number.

Answers (1)

2021-02-05

Let x be the number.
Eight times the number is 8x8x. Five more than eight times the number is then \( 5+8x\).
Twenty-one less than the number is \(x−21\).
Since five more than eight times the number is the same as twenty-one less than the number, then \(5+8x=x−21\). Solving for x gives:
\(5+8x=x−21\)
\(5+7x=−21\)
\(7x=−26\)
\(\displaystyle{x}=−{\frac{{{26}}}{{{7}}}}\)
The number is then \(−\frac{26}{7} ​\)

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