The question is incomplete:
Tommy bought a total of 20 game cards some of which cost $0.25 each and some of which cost $0.15 each. If Tommy spent $4.20 to buy these cards,how many cards of each type did he buy?
Answer:
He bought 12 cards that cost $0.25 and 8 cards that cost $0.15.
Explanation:
From the information given, you can write the following equations:
x+y=20 (1)
0.25x+0.15y=4.20 (2)
First, you can solve for x in (1):
x=20-y (3)
Now, you can replace (3) in (2):
0.25(20-y)+0.15y=4.20
5-0.25y+0.15y=4.20
5-0.10y=4.20
5-4.20=0.10y
0.80=0.10y
y=0.80/0.10
y=8
Finally, you can replace the value of y in (3) to find x:
x=20-y
x=20-8
x=12
According to this, he bought 12 cards that cost $0.25 and 8 cards that cost $0.15.