Simplifying radical expressions expression is important before addition or subtraction because it you need to which like terms can be added or subtracted. If we hadn't simplified the radical expressions, we would not have come to this solution. In a way, this is similar to what would be done for polynomial expression.
2/3=14/21 and 5/7=15/21 so 14/21+15/21=29/21 or 1 and 8/21
