Since the colorblindness is located on the X chromosome, the man must have inherited his colorblindness from his mother.
<h3>X-linked traits</h3>Women are XX while men are XY.
Also, the X chromosome in XY always comes from the mother.
Since the man is affected for colorblindness but his brother is not, it means that only one X chromosome of the mother is affected while the father can be affected or otherwise.
Assuming the father is free from colorblindness and the allele is represented by c:
x
Thus, the man's genotype is and it comes from the mother.
More on X-linked traits can be found here: brainly.com/question/9830755