Question

Sophia received some red-, green-, blue-, and yellow-colored balls.
The total number of balls is 15.

Upon counting, she observed:
1. The number of green balls is 2 less than the number of red balls.
2. The number of blue balls is twice that of the red balls.
3. The number of yellow balls is two more than that of the red balls.

How many red balls did she receive?

• A. 4
• B. 1
• C. 3
• D. 2

Answer 1

The correct option is C 3

Sophia has a total of 15 balls.

Let us assume that she has 'x' number of red balls.

We will make a table to determine the number of each colored ball.

Color	Number
Red	x
Green	x – 2
Blue	2x
Yellow	x + 2

So, upon adding all the balls, we get:
x + x – 2 + 2x + x + 2 = 15
⇒ 5x = 15

Dividing both the sides by 5, we get:
$\Rightarrow \frac{5x}{5}=\frac{15}{5}$
$\Rightarrow x=3$

We know, 'x' represents the number of red balls.

Hence, Sophia received 3 red balls.