<human>:  In a 90-minute soccer game, Mark played 20 minutes, then rested after. He then played for another 35 minutes. How long was he on the sideline?
<bot>: How many minutes did Mark play? ** Mark played for a total of 20 + 35 = <<20+35=55>>55 minutes.
How many minutes was Mark on the sideline? ** So, he was on the sideline for 90 - 55 = <<90-55=35>>35 minutes.
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