6Element X decays radioactively with a half life of 5

Last updated: 7/9/2022

6Element X decays radioactively with a half life of 5 minutes. If there are 390 grams of Element X, how long, to the nearest tenth of a minute, would it take the element to decay to 170 grams? Given the equation y = a(0.5)^t/h with y = 170, a = 390, h = 5 Find t.