Solving a decimal problem

Question

In Routine #1, she burns 40 calories walking. She then runs at a rate that burns 7.3 calories per minute.

In Routine #2, she burns 24 calories walking. She then runs at a rate that burns 10.5 calories per minute.

For what amounts of time spent running will Routine #1 burn fewer calories than Routine #2?

Use t for the number of minutes spent running, and solve your inequality for t

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Answer 1

Routine #1: calories = 40+7.3t

Routine #2: calories = 24+10.5t

40+7.3t < 24+10.5t

Subtract 24 from both sides

16+7.3t < 10.5t

Subtract 7.3t from both sides

16 < 3.2t

Divide both sides by 3.2

5 < t

For times greater than 5 minutes, Routine #1 will burn fewer calories than Routine #2.