This is a proportion problem and the given information allows us to formulate the equation below:
5 tickets/$17.50 = 7 tickets/x,
where x is the cost of 7 lottery tickets. We can solve this equation by first cross multiplying.
5 tickets × x = 7 tickets × 17.50 $
Carrying out the product on the right-hand side, we get;
5 tickets × x = 122.5 tickets·$
We can solve for x by dividing both sides of the equation by 5 tickets.
(5 tickets × x)/5 tickets = 122.5 tickets·$/5 tickets
Carrying out the division, we get a 1 on the left-hand side and a 24.5 on the right-hand side.
1x= 24.5 $
We can drop the 1 next to x, to get x= 24.5 $. It would cost Jordy $24.50 to buy 7 lottery tickets.