Let Y = number of yellow marbles

R = number of red marbles

"16 in total" means:

Y + R = 16

"number of yellow marbles is 1 more than 2 times the number of red marbles" means:

Y = 1 + 2R

Now, you have a very important **choice:**

** a) you may solve for Y**

** or**

** b) you may solve for R and then remember to solve for Y (asked by the problem)**

Let's substitute for R and solve for Y directly.

R = 16 - Y [from first equation]

Y = 1 + 2(16-Y) [from second equation]

Y = 1 + 32 - 2Y

3Y = 33

** Y = 11**

**There are 11 Yellow marbles.**

Check::

From Y+R = 16, there are 5 Red marbles

Is 11 = 1 + 2(5) ?

11 = 11 ?yes