Explanation

Use the identity x^3 + y^3 + z^3 - 3xyz = (x+y+z)(x^2+y^2+z^2-xy-yz-zx). Now x^2+y^2+z^2 = (x+y+z)^2 - 2(xy+yz+zx) = 100 - 36 = 64, so the second bracket is 64 - 18 = 46. Multiplying by (x+y+z) = 10 gives 460. Hence option (c).