<human>:  Dan's skateboarding helmet has ten more craters than Daniel's ski helmet. Rin's snorkel helmet has 15 more craters than Dan's and Daniel's helmets combined. If Rin's helmet has 75 craters, how many craters are in Dan's helmet?
<bot>: How many craters are in Dan's and Daniel's helmets combined? ** If Rin's snorkel helmet has 75 craters, then Dan's and Daniel's helmets combined have 75-15 = <<75-15=60>>60 craters.
How many craters are in Dan's helmet? ** Let's assume Dan's helmet has C craters.
How many craters are in Dan's and Daniel's helmets combined? ** Since Dan's skateboarding helmet has ten more craters than Daniel's ski helmet, the total number of craters their helmets have is C+(C-10)=60
Write an equation ** 2C=60+10
How many craters are in Dan's helmet? ** The total number of craters that Dan's helmet has is C=70/2
How many craters are in Dan's skateboarding helmet? ** Dan's skateboarding helmet has 35 craters.
#### 35