I've been working on math this morning, and these two equations I can't figure out. I have a test tomorrow and want to understand how to set them up in case theyre on the test. Equation 1 Uranium 235 is used as fuel for some nuclear reactors. It has a half-life of 710 million years. How long will it take 10 grams of uranium 235 to decay to 1 gram? --- answer is 2,360 million years Equation 2 You are trying to determine the half-life of a new radioactive element you have isolated. You start with 1 gram, and 2 days later you determine that it has decayed down to 0.7 grams. What is its half-life? --- answer is 3.89 days I've been trying various ways of setting these up with pe^rt and A(.999879)^t and simplifying with logs to no avail. If someone can help me please do!