Is 2/8 greater than 1/5

Yes.  Find a common denominator between 2/8 and 1/5.  2/8 simplifies to 1/4, so we're going to instead find the least common denominator between 1/5 and 1/4.  The least common multiple of 4 and 5 is 20.  In order to change 1/5 to something / 20, we need to multiply both the numerator and denominator by 4: 4/20.  For 1/4, we need to multiply both the numerator and denominator by 5: 5/20.  So, 1/4 (2/8) is greater than 1/5.

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable