The table shows the number of slices of pepperoni pizza and supreme pizza sold by a food truck on two separate days. it also shows the dollar amount taken in each day.

pepperoni supreme total
day 1 500 620 $3,730
day 2 500 430 $2,970
what is the cost of a slice of pepperoni pizza and the cost of a slice of supreme pizza? !

The answer is The price of pepperoni pizza slice is $2.5. The price of supreme pizza slice is $4.

p - the price of pepperoni pizza slice
s - the price of supreme pizza slice

According to the table:
On the day 1, 500 pepperoni pizza slices is sold for the price p (500p) and 620 supreme pizza slices is sold for the price s (620s) and the total amount was $3,730: 500p + 620s = 3730
On the day 1, 500 pepperoni pizza slices is sold for the price p (500p) and 430 supreme pizza slices is sold for the price s (430s) and the total amount was $2,970: 500p + 430s = 2970

So, we have the system of two equations:
500p + 620s = 3730
500p + 430s = 2970

Let's multiply both sides of the second equation by (-1):
500p + 620s = 3730
(-1)(500p + 430s) = (-1) * 2970

500p + 620s = 3730
(-1) * 500p + (-1) * 430s = (-1) * 2970

500p + 620s = 3730
-500p - 430s = -2970

Let's add up these two equations:
500p + 620s + (-500p - 430s) = 3730 + (-2970)

Rewrite it:
500p + 620s - 500p - 430s = 3730 - 2970
500p - 500p + 620s - 430s = 760
0p + 190s = 760
190s = 760
s = 760/190
s = 4
The price of supreme pizza slice is $4.

Now, replace s in one of the above expressions:
500p + 620s = 3730
500p + 620 * 4 = 3730
500p + 2480 = 3730
500p = 3730 - 2480
500p = 1250
p = 1250/500
p = 2.5
The price of pepperoni pizza slice is $2.5.