Please help me I have 10 minutes no scams I’m in 7th grade

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?

What are the soultion(s) to the quadratic equation 40- x^2=0

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5