Estimate a 15% tip on a dinner bill of $79.42 by first rounding the bill amount to the nearest ten dollars.

$12 tip

Step-by-step explanation:

For this problem let's first round our bill amount to the nearest ten dollars.  So $79.42 becomes $80.00.  From here we will simply need to find 15% of $80.00 which can be found simply through multiplication as follows:

$80.00 * 0.15 = ?

$80.00 * 0.15 = 12

So, we can say the estimated 15% tip for the bill is $12.

Cheers.

y=x+9

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step-by-step explanation: