b
e = 2+0.2*(b-2)

e \in N => b-2 = 5*x => b = 5x+2, e = 2+x

t = 6+0.2*(b-e-6)

t \in N => b-e-6 = 5*y => 5x+2-2-x-6 = 5y => 4x-6=5y => ...
  4x = 5y+6 ; x,y \in N

2x = 5*y' + 3 ; y = 2*y'

5*y' + 3 = 2x => y' = 2y'' + 1 => y = 4y'' + 2

=> 2x = 10y'' + 8 => x = 5y'' + 4

b = 5x+2 = 25y''+20+2 = 25y'' + 22
e =  x+2 =  5y''+6
t =  y+6 =  4y''+2+6 = 4 y''+8

/replace y'', n/

b = 25n+22
e =  5n+ 6
t =  4n+ 8

e > t <=> e = t + d, d \in N

e = 5n+6 = 4n+8+d => d = n-2 \in N => n > 2 => min n = 3