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

1,407.5 hours

step-by-step explanation:

we first convert all the time to hours and then sum them up.

there are 24 hours in 1 day, in 58 days, there are 24 x 58 = 1,392 hours.

there are 60 minutes in 1 hour, thus, 30 minutes will be equivalent to 30 / 60 = 0.5 hours.

therefore, the number of hours it will take mercury to complete a full rotation is 1,392 + 15 + 0.5 = 1,407.5 hours