Please clear this doubt. I am very much confused in this one

When Sir wrote (A1,A2,Ak)(Ak+1…An) Sir told total smoke by first bracket will be X and smoke generated by second bracket be Y So total Smoke will be (X+Y)%100.
Why Sir is confusing between Color and Smoke, Smoke will be XY and Sir told X=(A1+A2+…Ak)%100 But I think it will be A1A2*…Ak or something else in order like we have to find minimum. Please clear this doubt