Question

From the set {80, 19, 11}, use substitution to determine which value of x makes the equation true. 8x = 88 A. none of these B. 19 C. 11 D. 80

Answer 1

C. 11

Explanation:

Substituting, we have ...

8{80, 19, 11} ?= 88

{640, 152, 88} ?= 88

The value from the set that makes the equation true is x = 11.

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Alternate methods of solution (other than substitution)

It can be easier to make use of your knowledge of factoring:

8x = 8·11

x = 11

Or to make use of your knowledge of numbers (place value):

8·10 = 80

so x will not be very different from 10.