An appliance store offered gift cards to people making purchases. If a customer purchased a microwave, they received a $25 gift card. If a customer purchased a washing machine, they would get a $50 gift card. During this promotion, the store gave away 54 gift cards. The total value of the cards was $2,250. How many $25 dollar gift cards were given out during the promotion?

A. 12
B. 18
C. 36
D. 48

Let x be number of giftcard of 25$

y be number of giftcard of 50$

x+y=54

x=54-y. equation 1

25*x+50*y=2250

25(54-y)+50y=2250

1350-25y+50y=2250

25y=2250-1350

25y=900

y=36

put value of y in equation 1

x=54-36

x=18

the sum of all the angles in a triangle are equal to 180

so you can add   the 3 given angles together to equal 180:

5y + 2y + 2y = 180

or since all three angles have the same letter, combine the 3 angles to equal 180:

9y = 180