Answer:
C
Step-by-step explanation:
Let the cost of a pack of gum 20 years ago = x cents
Given, present cost of a pack of gum = 75 cents
Given, present cost of a pack of gum is 3 cents less than three times what the pack costs 20 years ago.
So,
[tex]75 + 3 =3x[/tex]
[tex]75= 3x -3[/tex]
[tex]3x-3=75[/tex]
Therefore,
Equation , [tex]3x-3=75[/tex] , can be used to find the cost of the gum 20 years ago.