Olivia's price would be determined by 5x-2.50, because she bought 5 greeting cards and got 2.50 off.
Alexandra's price would be determined by 4x-1, because she bought 4 cards and got 1.00 off. Since they both paid the same, you set the two equations equal to each other
5x-2.50=4x-1, subtract 4x to the other side so now you have
x-2.50=-1, add 2.50 to the other side so now you have
x=1.50
The price of each card is 1.50
