Oasis b is 25 km due east of oasis a. starting from oasis a, a camel walks 24 km in a direction 20° south of east and then walks 7.0 km due north. how far is the camel then from oasis b?

Imagining a Cartesian coordinate plane, let A be at 0,0 and B be at 25,0 
The camel first walks 24cos20° in the x direction and -24sin20° in the y direction. This puts him at x = 22.55, y = -8.21 
He then increases his y value by 7 so:

y = -8.21 + 7 =  -1.21
Ergo, the camel's distance from B is 

D = √ ((25-22.55)² + (-1.21-0)²) = 2.73 km