Answer:
There are 28 red marbles and 56 green marbles in the bag.
Step-by-step explanation:
Let's define:
R = number of red marbles in the bag.
G = number of green marbles in the bag.
We know that:
"There is a total of 84 marbles in the bag"
Then we can write this as:
R + G = 84
"The bag has twice as many green marbles as red marbles"
Then:
G = 2*R
So we have two equations:
R + G = 84
G = 2*R
This is the system of equations we need to solve.
To solve this, we usually start by isolating one of the variables in one of the equations, here we can see that G is already isolated in the second equation, then we can ignore the first step.
Now that we have an isolated variable, we can replace it in the other equation, then we can replace the second equation in the first one to get:
R + G = 84
R + (2*R) = 84
3*R = 84
R = 84/3 = 28
This means that there are 28 red marbles in the bag.
Now we can use the equation:
G = 2*R
To find the number of green marbles, where we need to replace R y 28, then we get:
G = 2*28 = 56
Which means that there are 56 green marbles.