8. Rosie needs to make $75. If she were to get a $1.25/hr raise, it would take her 2 hours less time to make that much money. How long would she have to work at her current rate?

Since this is a word problem, we first need to define our the unknown. In this problem, they are asking how long would it take ate her current rate. So we

let *x* = how long it would take her at her current rate.

Her current rate would then be 75/*x*. If she worked two hours less
for the $75 her rate would be 75/(*x* - 2). You would need to add $1.25
to her current rate to get the higher rate. This gives us the
equation

where we express the $1.25 as $5/4.

This gives us a rational equation. Clear denominators. The
smallest common denominator is 4*x*(*x* - 2). Multiply both sides.

Since the left side has two terms, we must multiply both of them.

Assemble the surviving factors.

Remove parentheses.

At this point we see that we have a quadratic. To get all of the
terms on one side, all we have to do is to subtract 300*x* from both
sides. That gives us

First factor out a factor of 5 from all of the terms on the left.

Since 5 is not 0, we can divide both sides of the equation by 5.

Factor

Set the factors equal to zero.

*x* - 12 = 0 *x* + 10 = 0

*x* = 12 *x* = -10

Check: (In the English)

If *x* = 12 then she worked for 12 hours and made $75/12hr =
$6.25/hr. If she had worked 2 hours less she would have made the $75
in only 10 hours, and $75/10hrs = $7.50/hr, which would be $1.25/hr
more, and it checks.

If *x* = -10, then she worked for -10 hours. There are several ways
of interpreting that. One interpretation would be that she missed 10
hours of work. But if she made $75 by missing 10 hours of work then
it is costing her $7.50/hr to go to work. One wonders what she does
for a living. If she had worked 2 hours less then she would have
missed 12 hours of work, and if she came out $75 ahead after missing
12 hours of work, then she would have been losing only $6.25/hr which
is $1.25/hr better than losing $7.50/hr. Most authors would reject
this solution as being too wierd, but that is not as much fun..