Answer:
15/2 or 7.5
Step-by-step explanation:

distribute 5/6 to each number

change the fraction 10/3 so that it will have the same denominator as 5/12
= 40/12

divide both sides by 5/6


Undefined terms is the category its belongs to.
(6 + 3) + 21 = 6 + (3 + 21)
It's an ASSOCIATIVE PROPERTY
(a + b) + c = a + (b + c)