smc

Using difference of squares to factor the left term, we get $$\frac{100^2-7^2}{70^2-11^2}\cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}=\frac{(100-7)(100+7)}{(70-11)(70+11)}\cdot \frac{(70-11)(70+11)}{(100-7)(100+7)}.$$ Cancelling all the terms, we get $\boxed{1}$ as the answer.