Question

What 2/3 + 5/7 complete denominators

Answer 1

You have to find common denominators. We can look at 3 and 7 and we know that nothing X 3 would equal to seven. So, we have to multiply
2/3 X 7 + 5/7 X 3
When we do that, we get 14/21 + 15/21
So when we add, the answer is 
29/21
When we look at that, we have to see if it can be reduced. We know that both 7 and 3 can go into 21 but can they go into 29? No, so therefore, the answer cannot be reduced 
Final answer is 29/21

Answer 2

Multiplying numerators and denominators to get the LCD in all fraction denominators

2 × 7 + 5 × 3
------------------
3 × 7 + 7 × 3

Then rewriting the equation with the equivalent fractions

__14__ 15
= ----- + -----
__21 __21

With like denominators we can operate on just the numerators

__14 + 15
= ------------
___21

__29
= -------
__21

Simplifying the answer

__29
= -------
__21

___8
= 1 -------
___21