green is composed of the yellow wavelength and the blue wavelength

1. You are confusing wavelengths and photoreceptors. All the colors in the rainbow have a wavelength - both yellow and green. There are colors, like pink, that don’t have their own wavelength - and white is one of these colors.
2. Between green and yellow, yellow is the one who doesn’t have its own photoreceptor in the human eye and thus the yellow we see is actually composed of red and green.
3. The yellow + blue = green thing is a concept of subtractive colors - which means the formula is actually white - yellow - blue = green.