We know that in 8 hours, Sal has $7.50. Then, in 10 hours, Sal will have

Now, we must convert the mixed fraction into a simple fraction form:

so, we must compute

since 8 times 7.50 is 60 and 2 times 3/2 is 3, we have

Finally, since 3 times 7.50 is 22.5, we get

and the answer is $82.5