Does anyone know how to solve (2 times x) + 5 =31

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?

If f(x) = 4 - x2 and g(x) = 6x, which expression is equivalent to (g-f)(3)? 06-3-(4 + 3)2 06-3-(4-33 6(3) - 4 +32 6(3) -4 -32

Which of the following is an example of a rational number? a. π b. √ 9 c. √ 8 d. 3.8362319