Answer is **220**

i) 1 – 3 + 4 = 100,

If we solve it we get;

1 – 3 + 4 = -2+4 = 2

So **2 = 100**.

ii) 4 – 6 + 9 = 999

we get **7 = 999**

iii) 2 – 6 + 7 = 879

We get **3 = 879**

Now we need to solve the last equation for which we need the answer;

So 3 -3 +6 = 6

we need to find the value of 6 which from above (i) + (ii) – (iii);

So **100 + 999 – 879 = 220**

So **6 = 220**