Let R, B, G and Y be the values of the Red, Blue, Green and
Yellow gifts respectively. To solve the problem, we use the
following algebraic equations:
R + 2B = 2G
where x is an integer representing the number of yellow gifts.
Solving for x, it can be shown that a Green
gift is worth 4 Yellow gifts, a Blue gift is worth 3 Yellow gifts, and a Red
gift is worth is worth 2 Yellow gift.