<human>:  A camping site recorded a total of 150 campers for the past three weeks. Two weeks ago, there were 40 campers which was 10 more than the number of campers three weeks ago. How many campers were there last week?
<bot>: How many campers were there three weeks ago? ** Three weeks ago, there were 40 - 10 = <<40-10=30>>30 campers.
How many campers were there from three to two weeks ago? ** The total number of campers from three to two weeks ago is 30 + 40 = <<30+40=70>>70.
How many campers were there last week? ** Hence, there were 150 - 70 = <<150-70=80>>80 campers last week.
#### 80