How would I set these up to find the values of the variables? I know that I need to set them equal to each other but I don't know how.

Element x decays radioactively with a half life of 8 minutes. if there are 450 grams of element x, how long, to the nearest tenth of a minute, would it take the element to decay to 37 grams?

The number of branches on a tree demonstrates the fibonacci sequence. how many branches would there be on the next two levels of this tree? 13 | | | m branches

Select the number of ways in which a line and a circle can intersect