# I am grammatically correct

Algebra Level 5

Let $$P(x) = x^4 - ax^3 + bx^2 - cx + 30$$ be with real values $$a,b,c$$. Such that its positive real roots $$r_1, r_2, r_3, r_4$$ satisfy the equation $$6r_1 + 10r_2 + 15r_3 + 30r_4 = 120$$. What is the value of $$(c-b)^2 - a^2$$?

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