Which term defines a well-tested, scientifically supported statement that explains how something works?

The correct term is - theory.

Explanation:

A theory is a well tested, scientifically proven and supported over a period of time repeatedly that we'll substantially explain how any natural phenomenon or something work.

The theory is a well-tested explanation whereas the hypothesis is presumption based on prior knowledge of experiments.

Thus, the correct term is - theory.

the way that the mass of carbon can be conserved through cellular respiration is through a process/law called the law of conservation of mass which even tho it undergoes a process, mass is not be destroyed or changed

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.