Answer:
A-100
Step-by-step explanation:
Use the Pythagorean therom.
a^2+b^2=c^2
6^2+8^2=c^2
36+64=100.
Hope this helps. Kinda confused me.
You could rewrite

as

and be tempted to cancel out the factors of

. But this cancellation is only valid when

.
When

, you end up with the indeterminate form

, which is why

is not a zero.
I would use is over of equals percent over 100 is woudl be 120% and of would be 75 then you would put x over 75
If Sharon is 3 years younger, then it's s = 3-b. However, it's twice her brothers age, which makes the formula our final answer, A, or 
From my understanding your asking what 20% of $48 is.
in that case it would be $9.60