#### Answer

(a) $C=2x+3$
(b) \$11
(c) 6 calzones

#### Work Step by Step

(a) There is a flat delivery fee of \$3 and an individual cost of \$2 per calzone. Thus the total cost is:
$C=2x+3$
(b) We plug in $x=4$:
$C=2(4)+3=8+3=11$
(c) We plug in C=15 and solve:
$C=2x+3=15$
$2x=12$
$x=6$
So you can order 6 calzones.