[This problem is the same as answering: 3^? = 8.7].

We cannot find log₃8.7 on a calculator. We need to use the change of base formula.

In this case, b = 3 and x = 8.7.

So

CHECK: By calculator, 3^1.9691414 = 8.6999989.

[We could have used natural logs as well, , which will give us the same answer.]