Cost in dollars a= cupcakes b=cookies. 2a+1.5b
a. The cost for one cupcake is $2 and the cost for one cookie is $1.50
b. The total cost for 6 cupcakes and 6 cookies is $21
$2(6)+ $1.50(6)=?
$12+$9= $21
c. Is $20 enough to buy 7 cupcakes and 4 cookies? Yes
$2(7) + $1.50(4)
$14+$6=20
7 cupcakes and 4 cookies cost exactly $20