# 2 equations, 3 variables!

Algebra Level 4

$\large { \begin{cases}a-7b+8c=4 \\ 8a+4b-c=7 \end{cases} }$

Let $a,b$ and $c$ be real numbers satisfying the system of equations above. Find the value of $60(a^2-b^2+c^2)$.

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