Numric patter find the missing number? 160,80,60,20( _ )5

Rearrange the formula c^2 = a^2 + b^2 for b

This is my question~~ ( r ^ 4 - 2r ^ 3 - 23 r ^ 2 - 4r - 32)÷(r+4) ~~ i must use long division to solve it : / i was wondering if anyone world like to solve it. and if so, share step-by-step explanations! you! ❤

Which type of graph would allow us to quickly see how many students between 100 and 200 students were treated?