4y-x=2x-4=x+y
solve for x

a system of equations , as below

Step-by-step explanation:

4y-x

2x-4

x+y

use any two of the above to find a formula for one of the variables since they are all equal to each other.. btw.. it makes it much easier .. that they are all equal.  :)

2x-4=x+y ⇒ x-4=y   use this to plug into the y in the top formula

4(x-4)-x=2x-4 ⇒ 4x-16-x=2x-4 ⇒ 3x-16=2x-4 ⇒ x=12  yay! ;) now plug in 12 for x

2(12)-4=(12)+y ⇒ 24-4 = 12 +y ⇒ 8=y   yay ! now we have both x and y

x=12

y= 8

this checks by plugging in the two number found for x & y  (btw I had to try this about 4 times ) :P  I kept messing up the algebra  which is s easy to mess up.  

the answer is a

step-by-step explanation:

constant of proportionality = 3 and the equation is c = 3p.

step-by-step explanation:

c = kp   where c = amount of caffeine in mg., p = oz of pepsi and k is the constant of proportionality.

substituting the values given:

24 = 8k

k = 3.

the same value of k will be obtained if we substitute the other given values.