一套西服原价210元,打九折后降价____元。
—I think it was not good.It was a(n) performance.
24÷6____4×6
12+4____4×4
15-5____15÷3
已知⊙O1和⊙O2的半径分别为4和5,且O1O2=8,则这两个圆的位置关系是( )