Answer:
Uncle's lawn paid the best (see explanation)
Explanation:
The earning rate for the various lawns was ...
- neighbor: $10/(1/2 h) = $20/h
- uncle: $30/(3/2 h) = $20/h
- community center: $30/(2 h) = $15/h
In this context, "paid the best" can be interpreted different ways. On the one hand, it can mean "paid the most per hour of work". No single job "paid the best" according to that meaning, as both the neighbor and the uncle paid at the rate of $20 per hour.
It can also mean "paid the most". No single job "paid the most", as both the uncle and the community center paid $30 for the work done.
We might say the uncle's job paid the best, because it both paid at the highest rate per hour and paid the most money.