Let U = the number of videos Uma watched
Ekon = U - 17
Kelsey = (U - 17) + 43 = U + <<(-17)+43=26>>26
U + U - 17 + U + 26 = 411
3U + 9 = 411
3U = 402
U = <<134=134>>134
Kelsey = 134 + 26 = <<134+26=160>>160 videos
Kelsey watched 160 videos.
#### 160