Question 91717
160^1/2 - 10^1/2

since both the terms have same root, we can write as 

(160-10)^1/2

150^1/2  

(25*6)^1/2   (150 can be split as 25*6)

square root of 25 is 5 , that is taken out

5*(6)^1/2

5*6*1.414( value of square root of 2 is 1.414)

42.42

2) -7x^3/5 - 8x^3/5

here x^3/5 is common between the two terms

Taking the common factor , we have

 ( -7-8)x^3/5

-15x^3/5

 Hence the solution