Answer:
a
Step-by-step explanation:
The mean is calculated by adding up all of the given numbers and dividing by the number of numbers.
Lets, for ease of understanding, say that the first three number were 64...
Mean=(64+64+64)/3=192/3=64
Now, lets solve for the mean where 'x' is the unknown fourth number and 128 is the mean. (since, the answer said that when the fourth number was added the mean, 64, was doubled '64*2=128')
128=(64+64+64+x)/4
128=(192+x)/4
Multiply both sides by 4
512=192+x
subtract 192 from both sides
320=x
The missing number is 320..
Now lets double check our work.
Mean=(64+64+64+320)/4=512/4=128
Answer=320
It should be -3x but i could be wrong
Answer:
56 eggs
Step-by-step explanation:
If 
of all eggs are green, 
of all are blue, then
of all eggs are red.
We know that there are 26 red eggs
![26\text{ eggs }-\dfrac{13}{28}\\ \\x\text{ eggs }- 1[=\dfrac{28}{28}]](https://tex.z-dn.net/?f=26%5Ctext%7B%20eggs%20%7D-%5Cdfrac%7B13%7D%7B28%7D%5C%5C%20%5C%5Cx%5Ctext%7B%20eggs%20%7D-%201%5B%3D%5Cdfrac%7B28%7D%7B28%7D%5D)
Make a proportion
![\dfrac{26}{x}=\dfrac{\frac{13}{28}}{1}\\ \\26\cdot 1=x\cdot \dfrac{13}{28}\ [\text{Cross multiply}]\\ \\13x=26\cdot 28\ [\text{Multiply by 28 to get rid of fraction}]\\ \\x=\dfrac{26\cdot 28}{13}\ [\text{Divide by 13 to get x}]\\ \\x=2\cdot 28\\ \\x=56](https://tex.z-dn.net/?f=%5Cdfrac%7B26%7D%7Bx%7D%3D%5Cdfrac%7B%5Cfrac%7B13%7D%7B28%7D%7D%7B1%7D%5C%5C%20%5C%5C26%5Ccdot%201%3Dx%5Ccdot%20%5Cdfrac%7B13%7D%7B28%7D%5C%20%5B%5Ctext%7BCross%20multiply%7D%5D%5C%5C%20%5C%5C13x%3D26%5Ccdot%2028%5C%20%5B%5Ctext%7BMultiply%20by%2028%20to%20get%20rid%20of%20fraction%7D%5D%5C%5C%20%5C%5Cx%3D%5Cdfrac%7B26%5Ccdot%2028%7D%7B13%7D%5C%20%5B%5Ctext%7BDivide%20by%2013%20to%20get%20x%7D%5D%5C%5C%20%5C%5Cx%3D2%5Ccdot%2028%5C%5C%20%5C%5Cx%3D56)
