Help geometry

6+b+c = 15

b+c = 15

b = 15 - c

6^2 + b^2 = c^2

plug in b:

6^2 + (15-c)^2 = c^2

36+225+c^2-30c = c^2

cancel out the c^2 and combine constants

261 - 30c = 0

30c = 261

c = 261/30

:)

A right triangle has legs of length  6 and b, and a hypotenuse of length c.                                                                      The perimeter of the triangle is 15. Compute c.

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a = 6             b + c = 9           b = 9 - c           P = 15

a² + b² = c²

6² + (9 - c)² = c²

c = 6.5                (b = 2.5)