solve n/4 -1 = n/5?

5n - 20 = 4n
5n - 4n = 20
n = 20

n/4(4)(5)-1=n/5(5)(4)
5n-20=4n
n=20

(N/4)-1=(n/5)
(N/4)-(N/5)=1
(5N - 4N)/20=1
N/20=1
N=20

n/4 - 1 = n/5
n/4 - n/5 = 1
5n/20 - 4n/20 = 1
(5n - 4n)/20 = 1
n/20 = 1
n = 20

n/4 - 1 = n/5 multiply through by 20
5n - 20 = 4n
n = 20

Each side should be multiplied by 20.
(20* n/4) -(20*1) = (20*n/5)
=> (5n)-(20)=(4n)
=> (5n)-(4n)=(20)
=> n = 20

n/4 - 1 = n/5
subtract n/4 from both sides:
-1 = n/5 - n/4
change so that all have the same denominator (multiply the n/5 by 4/4; mult. the n/4 by 5/5; mult. the -1 by 20/20, you can do this because each of those values [4/4, 5/5 and 20/20] equal one):
-20/20 = 4n/20 - 5n/20
multiply EVERYTHING by 20 to cancel all of the bottom 20's out
left with:
-20 = 4n - 5n
-20 = -n
divide each side by -1
20 = n

BRACKETS! n/(4-1) is different from (n/4) - 1

You mean the latter

5n/4 - 5 = n
5n - 20 = 4n
n = 20

n/4-1=n/5
or n/4-n/5=1
or n/4*5/5-n/5*4/4=1
or 5n/20-4n/20=1
or n/20=1
or n = 20