Settings: There are X computers.

3(X+ 1)=4(X- 1)+3

X=4

Employee: (4+ 1) * 3 = 15

2."253"

Suppose: one is X, ten is Y, and one hundred is Z.

According to the meaning, then: y = x+z

Y-x = 2 = z (so the hundredth is 2)

So: 200+x+10y+99 =100x+10y+2.

Namely: 299+x = 100x+2.

99X=297

X=297/99=3

Y = 5, because X = 3 and Z = 2.

Checking calculation: 253+99 = 352