物理电学计算题.A 30 µF and 60 µF capacitor are connected

物理电学计算题.
A 30 µF and 60 µF capacitor are connected in series. The pair are then connected in parallel to a 10 µF capacitor. Find the equivalent capacitance.
一个30 µF 和一个60 µF的电容器连接（好像是串联吧.）然后并联了一个10 µF的电容器.那么找出相等的电容?（应该是这么翻译吧）
100 µF
9 µF
60 µF
30 µF
物理实在学得太差了,求大神指点!