If Robi contributed $4000, then Rudy contributed 1/4*4000 = $1000 more.
The total amount of money Rudy contributed is $4000+$1000 = $<<4000+1000=5000>>5000
Together, the contributed a total of $5000+$4000 = $<<5000+4000=9000>>9000
They made a 20% profit, a total of 20/100*$9000 = $<<20/100*9000=1800>>1800
When they decided to share the profit equally, each received $1800/2 = $<<1800/2=900>>900
#### 900