Answer:
5b + 4/3
Step-by-step explanation:
So if Jenny is 6b and her brother is half that he must be 3b. If her sister is four years older than her then she must be 6b + 4. To find the mean (or average) you add all the numbers and then divide by how ever many things you added together, so you would do:
Average = (6b+3b+6b+4) ÷ 3
= (15b+4) ÷ 3
= 5b + 4/3
