Dodo initially had 56 green pencils and 28 red pencils.
Step-by-step explanation:
Step 1:
Assume the number of green pencils is x and the number of red pencils is y. From the question, we have
[tex]x = 2y, x - 2y = 0[/tex], take this as equation 1,
[tex]x-42 = \frac{y}{2} = 2(x-42) = y, 2x - 84 = y, 2x-y = 84[/tex]
[tex]2x-y=84[/tex], take this as equation 2.
Step 2:
If we multiply equation 1 with 2 and subtract it from equation 2, we cancel out the x variable and can solve for the value of y.
[tex]2(x-2y) = 2x - 4y = 0[/tex], take this as equation 3.
By subtracting equation 2 from 3, we get
[tex]-3y = -84, y = \frac{-84}{-3}, y = 28.[/tex]
Step 3:
Substituting this value of y in any of the previous equations we will get x's value.
Here this value of y i.e y = 28 is substituted in equation 1.
[tex]x - 2(28) =0, x - 56=0, x = 56.[/tex]
So we have x = 56 and y = 28.
