step 1
Find out how much is the sales tax in Connecticut
we have
6.35%=6.35/100=0.0635
Multiply by $120.00
120.00*(0.0635)=$7.62
step 2
Find out how much is the sales tax in Missouri
we have
4.225%=4.225/100=0.04225
Multiply by $120.00
120.00*(0.04225)=$5.07
step 3
Find the difference
so
7.62-5.07=$2.55
therefore
the answer is $2.55