Please check answer and help with one of them:

1. check please
car in an accident speed of car is the s, d is length of skid=30 feet
f is coefficient=0.5
use formula to find
s=sqaure root of 30*f*d
My answer is 21.21 because I took square root of 30(0.5)(30)
2. this one is baffling to me-how do I do this one-3 times square root of (x+1) is less than or equal to 7 Please help-Thank you