x=cost of one of Tanya´s items.
Tanya spent: 3x
Tony spent:4(x-2.25)
We can suggest this equation:
3x=4(x-2.25)
We solve this equation:
3x=4(x-2.25)
3x=4x-9
3x-4x=-9
-x=-9
x=9
The individual cost of each person´s item would be:
cost of one of Tanya´s items=x=9
Cost of one of Tony´s items=(x-2.25)=6.75
Answer: the cost of one of Tanya´s items was $9, and the cost of one of Tony´s items was $6.75, the equation used was [ 3x=4(x-2.25) ] .
We check it out our answer:
Tanya spent: 3x=3(9)=27
Tony spent:4(x-2.25)=4(9-2.25)=4(6.75)=27
Because Tanya spent the same amount of money than Tony, and Tanya bought 3 items and Tony bought 4 items, this solution is right.