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What is the first step of an indirect proof of a number that is divisible by two

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

In the equation sqrt(n+5)-sqrt(11-10)=1. what is the value of n