All members of our painting team paint at the same rate. If $50$ members can paint a $3600$ square foot wall in $20$ minutes, then how long would it take for $25$ members to paint a $4000$ square foot wall, in minutes?
3600 / [ 50 *20 ] = 3.6 sq ft / min painted by one worker
So
4000 / [ 25 * 3.6 ] ≈ 44.44 min