Test 7 Section 3: #8

Let’s work backwards on this. If he saves 90% of his earnings, Ken needs to make $300 to save $270:


He makes $80 for the first 10 hours he works, so he needs to make $220 more to get to $300.

He’s making $10/hour for that last $220, so he’s going to have to work 22 more hours.

Of course, we can also construct an equation to solve this. First, as above, we know Ken worked for 10 hours at $8/hour, so for that time he made $80.

He’s making $10/hr for the rest of the week. We don’t know how many hours, so let’s use h for hours. He’ll make 10h dollars for the rest of the week.

That means in total he’ll make 80+10h dollars for the week.

He’s going to save 90% of what he makes, so his savings will be 0.9\left(80+10h\right).

He wants to save $270, so the equation we need to solve is 0.9\left(80+10h\right)=270:


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