Answer: you bought 8 of the 42-cent stamps and 12 of the 24-cent stamps.
Explanation:
This seems like a classic algebra problem. Let's call the number of 42 cent stamps x and the number of 24 cent stamps y. The total cost can be expressed as 42x + 24y, and since you bought 20 stamps in total, x + y = 20.
Now, you also know that the total cost is $6.24, so you have the equation 42x + 24y = 624 (since each dollar is 100 cents).
Now, you have a system of two equations:
x + y = 20
42x + 24y = 624
You can solve this system to find the values of x and y. Let me know if you want me to help with that!
Alright, let's solve the system of equations. We can use the substitution method or elimination method. I'll go with the elimination method.
Here are your equations:
x+y=20
42x+24y=624
First, let's multiply the first equation by 24 so that the coefficients of y in both equations match:
24x+24y=480
42x+24y=624
Now, subtract the first equation from the second:
(42x+24y)−(24x+24y)=624−480
This simplifies to:
18x=144
Now, divide both sides by 18 to solve for x:
x=8
Now that you have the value for x, plug it back into the original equation (1) to find y:
8+y=20
Subtract 8 from both sides:
y=12
So, you bought 8 of the 42-cent stamps and 12 of the 24-cent stamps.