Answer: Uhh
Step-by-step explanation:
Substitution.
Here is an example.
Let x be equal to 3 and y equal to 3.

From this we can conclude that the values of both x and y are equal to three therefore x and y have the same value and are equal.

Here in your case we have:

Hope this helps.
r3t40
6-2=4 whole number
4/5-1/5=3/5 fraction
put the fraction and whole number toger and you'll get
since the denominator is the same it's easier to subract
4 3/5 <--- answer
No 20.0000004 cannot be rational.