All you do is multiply 15 and 6 you get 90. then divide 90 by 9 and you get 10.
Answer:

Step-by-step explanation:
Given

Required
Determine the roots
To get the root of the function, then f(b) must be 0;
i.e. f(b) = 0
So, the expression becomes

Add 75 to both sides


Take square roots of both sides


Reorder

Expand 75 as a product of 25 and 3

Split the expression




The options are not clear enough; however the roots of the equation are 
Answer:
104 cm^3
Step-by-step explanation:
2(1/2(6*4))+2(1/2(4*10)+(4*10)
2(1/2(24)+(2(1/2(40)+(40)
2(12)+2(20)+40
24+40+40
104 CM^3
2x + 10...the common number between these 2 terms is 2...so factor the 2 out
2(x + 5) <==