I think the answer is yes you can because they are both different things.
What I mean by that is that the United Stated as .151% of its people with hearing problems, and .093% with vision problems. So really adding them together just mixes it saying that .244% of people in the united states have either a vision or a hearing problem.
It doesn’t make it any more or any less people by adding them together. Therefore it’s not any more or any less probable to pick one or the other.
Hopes this helps.
Answer:
7 1/2 hours I believe is the correct answer. Hope it works!
Step-by-step explanation:

You need to remember the properties of exponents: multiplication adds the exponents, division subtracts the exponents.
If you multiply two powers with the same base, the result will be the base to the sum of the powers.
If you divide two powers with the same base, the result will be the base to the difference of the powers.
In your case you will this:

That is:

Or:
