Emily has been saving some money. Last night she counted 94 bills – in $1’s, $5’s, and $10’s – with a total value of $598. She noticed she has twice as many $5-bills as she has $1- bills. Let x represent the number of $1 bills, y represent the number of $5 bills, and z the number of $10 bills. Set up a system that could be used to find the number of $10 bills she has