Question

Angela is playing with red and black marbles. The number of red marbles she has is three
more than twice the number of black marbles she has. She has 42 marbles in all. Which
system of equations can be used to find the number of red marbles, R, and black marbles, B?o

Answer 1

Answer:

We will need two equations, one that adds up to the total number of marbles, and the other which writes one type of marbles in terms of the other.

For the first equation we know that:

$r + b = 42$

For the second we are told that "The number of red marbles she has is three  more than twice the number of black marbles she has."

So we simply translate this into an equation being:

$r = 2b + 3$