#### Answer

(a) $\$175.35$
(b) $\$5.45$

#### Work Step by Step

(a)
We know that you order one of each type of shirt for yourself. From the table, the sum is:
$14.75+16.75+18.95+21.95=\$72.40$
In addition, you order three XXL shirts at $\$21.95$ each plus \$$2$ for the size. Adding this to the previous total, we get:
$72.40+3*21.95+3*2=72.40+65.85+6=\$144.25$
We calculate the shipping based on this total, which comes out to $\$11.95$ plus $\$4.25$ for the addition address. This brings the total to:
$144.25+11.95+4.25=\$160.45$
Finally, we need to include the cost of the monograms (2 at $\$4.95$ each) and the gift box ($\$5$):
$160.45+2*4.95+5=\$175.35$
(b)
We see from part (a) that the cost of the shirts for yourself (with monograms) comes out to:
$14.75+16.75+18.95+21.95+4.95*2=\$82.30$
And the cost of the shirts for dad (with gift box) comes out to:
$21.95*3+3*2+5=\$76.85$
Thus the difference is:
$82.30-76.85=\$5.45$