For \(r = 0, 1, \ldots, 10\), let \(A_r\), \(B_r\), and \(C_r\) denote, respectively, the coefficients of \(x^r\) in the expansions of \((1+x)^{10}\), \((1+x)^{20}\) and \((1+x)^{30}\). Then \(\displaystyle\sum_{r=1}^{10} A_r(B_{10}B_r - C_{10}A_r)\) is equal to