Answer:
week number: 11 if you do count the first time they got the money or week number 10 if you don't count the first time they got the money
Explanation:
First time they got money: Julie: 41,200 Kelsey: $400
week 1: Julie : $1,180 Kelsey: $440
week 2: Julie: $1,140 Kelsey: $480
week 3: Julie: $1,100 Kelsey: $520
week 4: Julie: $1,060 Kelsey: $560
week 5: Julie: $1,020 Kelsey: $600
week 6: Julie: $980 Kelsey: $640
week 7: Julie: $940 Kelsey: $680
week 8: Julie: $900 Kelsey: $720
week 9: Julie: $860 Kelsey: $780
week 10: Julie: $820 Kelsey: $820