Tell which equation you use to solve for one of the variables when solving the system by substitution: 2x + 3y = 5 or 4x - y =3 // pl : $)

You can using any equation you want to solve for one of the variables. For instance,  if you want to solve for x you turn one of the equations so y is by its self

2x + 3y = 5
 4x - y =3

I am going to use 4x - y =3
-y = -4x + 3
y = 4x -3
Now you can substitute 4x - 3 for y  in 2x + 3y = 5 and solve for x
2x + 3y = 5
2x + 3(4x - 3) = 5

It is 2 out of 8 she will pick green and 3 out of 7 she will pick green but red and green would be 5 out of 5 so 50% chance