We can find equals to the given components

Then you have to find equal for f2= 100cos(170) ,100sin(170) which is 

Substract the vectors to find F3 coordinates 


With theese new coordinates it is possible to find the direction and magnitude by using arc tan and square rooting. You should make 

 and plug it to the arc tan function tan-

. You will obtain direction 89.54, then find magnitude of the square root of 36315.4 --
