Ok so first we need to find out how many have either red or brown hair, which is 1/4+1/6. here, we need to find a common denominator, which is 12. so we are going to multiply 1/4 by 3/3 and 1/6 by 2/2. this yields, 3/12+2/12=5/12. since the rest have black hair, we do 1-5/12 which is 7/12
First we need to make the fractions have the same denominator. the smallest common multiple of 4 and 6 is 12, and 1x3= 3, and 4x3= 12, so 3/12 of the participants have red hair. 1x2= 2, and 6x2=12, so 2/12 of the participants have brown hair. 3+2=5, so 5/12 of the participants have red OR brown hair, and there's 7 left. therefore 7/12 of the participants have black hair.
