Insert a rational and irrational number between 2/3 and 4/5
A rational number between 2/3 and 4/5 will be (2/3 + 4/5)/2 = (10+12)/(15×2) = 22/30 = 11/15
Alternate:
2/3 = 0.666… and 4/5 = 0.8
So an irrational number between the two can be any from 0.67, 0.68, 0.70, 0.75 etc.