Answer is $22.37:
You subtract $56.75 from $87.37,which equals $30.62, then you add the 2 checks that the bank didn't return and subtract that amount from the $30.62.
Unit rate means how much does it cost for 1 unit
140 for 18ft^2
divide by 18
140/18=7.77777777777777
so the unit rate is $7.78 per square foot
