The sum of the m numbers divided by m (which is the average) equals n^2. Then, the sum of the m numbers equals mn^2.
The sum of the n numbers divided by n (which is the average) equals m^2. Then, the sum of the n numbers equals nm^2.
The average of m+n numbers which is the sum of the m numbers plus the sum of the n numbers divided by (m+n) equals (mn^2+nm^2)/(m+n). This is mn(n+m)/(m+n). Then the factor (m+n) can be ruled out and the result is mn.
Answer:
19 birds
Step-by-step explanation:
First, I wrote my two equations:
5.5x +8.5y = 291.5
x + y = 41
Next, I got the variable y by itself in the second equation. Subtract x to get y = -x + 41. Then, I substituted what y equaled into the first equation. It should look like this: 5.5x + 8.5(-x+41) = 291.5. Distribute 8.5 to get 5.5x -8.5x + 348.5 = 291.5. Subtract 5.5x and 8.5x to get -3x. It should look like this: -3x + 348.5= 291.5. Subtract 348.5 from 291.5 to get -57. Now, you should have -3x = -57. Divide -3 from both sides, to get x = 19. So, there are 19 birds. If you want to go even further, 41-19= 22, which means there are 22 cats. Hope this helped!
