A. I took a educated guess
A:10
B:-8
You have to substitute all given numbers and solve
I believe the answer is 53 but im not 100% sure
4:50
x:2650
2650/50=53
2tan(x)
i. take the 2 out
ii. derivative of acos is -sin
iii. derivative of In is -ve inverse
so we have 2 times sin(x)/cos(x) hence 2tan(x)