CPM Homework Help : A2C Problem 8-33

Mary has an antique marble collection containing $40$ marbles. She has five more red marbles than blue and twice as many red as green marbles. Write a system of equations to find the number of each color of marble.

Hint:

Let $b=$ the number of blue marbles, $r=$ the number of red marbles,
and $g=$ the number of green marbles.

More Help 1:

$b+5=r\\2g=r\\r+g+b=40$

More Help 2:

Solve the system of equations using a combination of substitution and elimination.