Answer:
b
Step-by-step explanation:
did the unit test
Answer:
13 + 3x= 31
Step-by-step explanation:
First of all, you should know/notice that

You should also know how negative exponents work:

So, if you wanted

the answer would be x=3, but since you want 125 to be at the denominator, the answer is x=-3:

Here is you're answer:
In order to cross multiply you have to multiply the numerator and denominator of the first fraction by the bottom number of the second fraction and see if the equation is still true:
Therefore you're answer is "3 × 1 = 5 × 10."
Hope this helps!