Question 537963
First off, you need to know the Order of Operations. 
Parenthesis (or sometimes brackets)
Exponents and Roots
Multiplication and division (as they appear left to right)
Addition and Subtraction (also as they appear left to right)

So first, we need to add 0.2 and 0.8, since they are in parenthesis.

0.8
0.2
___
1.0

5(1)10
The rest is multiplication. 5 x 1 x 10 = 50