80.1 years, im not 100% sure of my answer though
Answer:
see below
Step-by-step explanation:
For simplifying expressions of this sort, there are four rules of exponents that come into play;

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I find it convenient to eliminate the fractions by adding the exponents, then rewrite any negative exponents as denominator factors.

We have that
the expression 2f + 4f + 2 – 3-------> we can group it (2f+4f)+(2-3)
(2f+4f)+(2-3)=(6f-1)
therefore
the expression [2f + 4f + 2 – 3] is equivalent to [6f-1]
if the expression [6f-1] for f=3 is 17
then
the expression [2f + 4f + 2 – 3] for f=3 is also 17
<span>let's check it
</span>[2*3 + 4*3 + 2 – 3]--------> [6+12+2-3]=[20-3]=17------> is ok
3: multiply the change per minute by how many minutes: 3.1x15=46.5. 5: Is your opinion, I can't tell you how to feel. But a negative times a negative is a positive, so if there is an even number of negatives no matter how many positives there are it will be positive, if there is an odd number of negatives it will be negative. :) Hope this helps!