pam is playing with red and black marbles. The number of red marbles she has is 3 more than twice the number of black marbles. She has 42 marbles in all. How many red marbles does she have?
A) 13 B)15 C) 29 D) 33

Question

pam is playing with red and black marbles. The number of red marbles she has is 3 more than twice the number of black marbles. She has 42 marbles in all. How many red marbles does she have?
A) 13  B)15  C) 29 D) 33

kropot72 · Answer

Let r = number of red
Let b = number of black
r + b = 42 .........1)
b = 42 - r ..........2)
2b + 3 = r ..........3)
Substituting the value of b found in 2) into 3)
2(42 - r) + 3 = r
84 - 2r + 3 = r
3r = 87

Can you find the value of r now?

anonymous · Answer

29

kropot72 · Answer

That's right! Hope you understand how to do it :)