Question 5.
To get the resultant of two vectors we add the two vectors given. 
In this case, <-6,5> and <6,-5> 
Therefore, <(-6+6), (5+-5)>
 = <0,0>
Question 6
The appropriate trigonometric ratio to use in the question is tan
Tan θ = opposite/ adjacent
θ is 70 degrees ( 90-20)
Opposite is 15 yd 
Adjacent is x
Therefore;
 Tan 70 = 15/x
 x = 15/tan 70
 x = 5.45955
 ≈ 5.5 yd
Thus, the value of x (nearest tenth) is 5.5 yd