Answer:
He would make $67.20 more a week if he got the increase.
Explanation:
10% of $16.80 is $1.68. Add $1.68 to $16.80. You get $18.48. Multiply that by 40 hours. You get $739.20. Next, subtract $672 from $739.20. Your answer to that is how much more he'll make if he gets the increase.