Write as a system of 3 equations:
\(3a = b+c\) (Equation 1)
\(5b = a+c\) (Equation 2)
\(c=80+b\) (Equation 3)
Sub in (Equation 3) into (Equation 2): \(5b = a+b+80\)
Simplify: \(b = {a \over 4}+20\)
Now, sub what we found for b, and (Equation 3) into (Equation 1): \(3a= {a \over 4} +20+80+ {a \over 4} +20\)
Solving, we find \(a = 48\)
Subbing the value of \(a\) we just found and (Equation 3) into (Equation 2), we get: \(5b = 48+80+b\)
Solving, we find \(b = 32\)
Plugging in what we found for the value of \(b\) into (Equation 3), we find that \(c = 112\).
Now do \(a + b+c\) to find your answer.