What is the sum of 3x cube - 2x + 8, 2x^+5x, and x cube + 2x^-3x-3

Asap! i'm not good math and i'm lost.

If a flying disk is 139 meters in the air and travels at an average of 13 m/s how long is it in the air

Suppose a laboratory has a 30 g sample of polonium-210. the half-life of polonium-210 is about 138 days how many half-lives of polonium-210 occur in 1104 days? how much polonium is in the sample 1104 days later? 9; 0.06 g 8; 0.12 g 8; 2,070 g