Two piglets are equal to three lambs.

Then 6 piglets are equal to 6÷2×3=9 lambs.

Each lamb: 1 12 ÷ (9+5) = 8kg.

Each piglet: 8× 3 ÷ 2 = 12kg.

2.

If 20 questions are answered correctly, you can get: 20×8= 160 points.

Now I only got 100, which is less: 160- 100=60.

For every mistake 1, 8 points are not allowed to be deducted, and 4 points are deducted. If one * * * is missing, it is 8+4= 12 points.

Wrong: 60- 12 = 5 questions

The comprehensive formula is: (20×8- 100)÷(8+4)=5 questions.

Got it right: 20-5= 15.