Result to Below Q

Chances are the below set of equations can be solved but the variables will not yield a unique value. In fact, there are infinite solutions to it.

(3) - (2):

20a + 20c = 4
=> (1)

So, in essense, you have only 2 equations, and three variables. So this set of equations has no unique solution. Hence, the set of solutions (a, b, c) can be:
(0.1, 0.15, 0.1) or (0.5, 0.05, -0.3), etc...

The solution can be expressed in the form of:

a = 1/5 - c
b = 1/8 + 1/4 c
c is real