10 ladders with 50 rungs have a total of 10*50=<<10*50=500>>500 rungs.
20 ladders with 60 rungs have a total of 20*60=<<20*60=1200>>1200 rungs.
In total there are 1200+500=<<1200+500=1700>>1700 rungs.
The client must pay 2*1700=$<<2*1700=3400>>3400.
#### 3,400