Demoness, where are you Fleeing to?

The second question: peering at the towering seven-layer tower, the red dots of light double on each level, make up a total of three hundred and eighty-one. How many lights are on each floor?

The problem is asking how many lamps there are on each of the seven-layer tower, where the number of dots on the lower floor is twice that of the upper floor, and the total red lamps known sum up to three hundred and eighty-one.

With hardly any deliberation, Li Xuan could quickly calculate the answer in his mind.

x+2x+4x+8x+16x+32x+64x=381

Therefore, there were three lamps on the seventh layer, six lamps on the sixth, twelve lamps on the fifth, twenty-four on the fourth, forty-eight on the third, ninety-six on the second, and one hundred and ninety-two on the first.

Li Xuan robustly wrote the answer on the rice paper: "Give me the third question!"

As the Siye of Guozi Bureau handed out the third question paper, he darted a glance at Zhen Huandou on the side. The latter was deeply furrowed his eyebrows, clattering on the abacus.

Meanwhile, Li Xuan looked at the third question — There are some unknown number of objects: when counted by threes, two are left; when counted by fives, three are left; when counted by sevens, two are left —

The problem asks when an unknown quantity of items is counted in threes, it leaves two; when counted in fives, it leaves three; when counted in sevens, it leaves two. How many items were there?

As before, Li Xuan quickly derived the formula — 70×2+21×3+15×2=233, 233-105-105=23.

So, the answer was twenty-three.