Given:
Let x be the number of the cards and y be the number of the package.
Given that the number of cards is at least 4 more than twice the number of packages.

Given that mailing costs no more than $500 and the cost of mailing a card is $3 and for a package, the cost is $7.

Substitute x=2y+4 in this equation, we get





Let y=37 and substitute in x=2y+4, we get


Hence the number of cards = 78 and the number of packages =37.
The total cost for this is $493 not more than $500.