Question

Alemu, Tulu, Kassa and Tegitu worked for 4 hours, 6 hours, 5 hours

Answer 1

As a group they were paid $1000 after putting in 4+6+5+5 = 20 worker-hours.
$1000/(20 worker-hours) = $50/(worker-hour)
Alemu received 4*$50 = $200
Tulu received 6*$50 = $300
Kassa and Tegitu each received 5*$50 = $250