Question

3/4,19/20,1/6,3/5,8/15 what is lcd

Answer 1

You just have to find the lcm or least common factors of the denominators which is 60.

Answer 2

The least common multiple of denominators
.. 4 = 2^2
.. 5
.. 6 = 2*3
.. 15 = 3*5
.. 20 = 2^2*5
is 2^2*3*5 = 60

The lowest common denominator is 60.