Let x be the number of pizzas purchased. For each card, write an expression for the amount of money left on the card after purchasing x pizzas.
For Keith
Keith received a gift card of $90 for a pizza restaurant. The restaurant charges $15 per pizza.
x numbers of pizza costs = $15x
Hence, the amount of money left on Keith's card after purchasing x pizzas =
$90 - $15x
For Mary,
Mary received a gift card of $110 for a different pizza restaurant. The restaurant charges $20 per pizza.
Hence, x number of pizzas cost =$20 × x
= $20x
Therefore, the amount of money left on Mary's card after she buys x pizzas =
$110 - $20x
Amount of money left on Keith's card in dollars = __________
Amount of money left on Mary's card in dollars=____________
Write an equation to show that the two cards have the same amount of money left on them [don't know how to do this part.
To find the equation that shows that the two cards have the same amount of money =
Equation 1 = Equation 2
$90 - 15x = $110 - 20x
Collect like terms
-15x + 20x = $110 - $90
5x = 20
x = 20/5
x = 4
Hence, anytime Keith and Mary buys 4 pizzas their gift card will have the same amount of money left on them.
