Step-by-step explanation:
part A:
she can buy 8 of $1 items and and 5 $2 since
[tex]8(1) + 5(2)= 8 +10 =[/tex] $18 < $20
she can buy 5 $1 items and and 7 $2 since
[tex]5(1) + 7(2)= 5 +14 =[/tex] $19 < $20
she can buy 5 $3 items and and 8 $2 since
[tex]3(1) + 8(2)= 3 +16 =[/tex] $19 < $20
part B:
let x represent $2 and y represent $1 , since she wants to spend below $20 this would be
[tex]2x +y<20[/tex]
part C:
refer to the attached graph for part c
the difference between the ordered pairs that falls on the line and the shaded area is 0