# A plumber charges $65 for a diagnostic check. After the check, it is$85 per hour for the work. With $320 in your wallet, how many hours of work san you afford? ##### 1 Answer 4 hours, assuming any portion of an hour worked is charged out as another hour. 4.2 hours if that assumption doesn't hold. #### Explanation: We have$320 in the wallet:

$320$

And it costs $65 for the diagnostic check, so that means we pay that from our 320: $320 - 65 = 355$And the plumber charges$85/hr, so we divide that into the money we have left:

$\frac{355}{85} = 4.2$ hours, and since I'm going to assume that this problem will have our plumber charging us for an hour for any portion of that hour worked, we can have 4 hours of work done.

We can also approach this problem by writing out one algebraic equation. It would look like this:

$\text{diagnostic check" + "number of hours" xx "fee per hour" = "total fee}$, where $\text{total fee" < "cash in wallet}$

we can drop numbers into this:

$65 + n \times 85 = \text{total fee}$, where $\text{total fee} < 320$

and so we can substitute in:

$65 + n \times 85 = 320$ to see the maximum n

and now we solve:

$n = \frac{320 - 65}{85} = 4.2$

and then round down to the closest whole number, or 4.