4. The set of months containing 30 days.
a. I = {January, March, May}
b. J = {February, April, June}
c. K = {June, July, August}
d. L = {June, September, November}
5. The set of secondary colors.
a. M = {red, green, yellow}
b. N = {brown, pink, blue}
c. O = {green, orange, violet}
d. P = {white, black, grey}