Answer:
The least common multiple, but you can use the greatest common factor, but at the end you have to simplify for it to be correct. 1 3/30
Step-by-step explanation: 4/15+5/6
Change 15 into a 30 by multiplying 2 to both sides.
Change 6 into a 30 by multiplying 5 to both sides.
so the new fractions are 8/30+25/30=33/30
The final fraction is 1 3/30.