What is the answer for 1/2(2a+4)

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?

Write a function for a rotation 90 degrees counter clockwise about the origin, point 0

Gabrielle's age is three times mikhail's age. the sum of their ages is 40 . what is mikhail's age? __ years old