Students in the fourth grade of primary school have not learned equations, and this problem should be solved by hypothesis.

Assuming that there are no problems in any question, you can get: 10*8=80 (points).

If you make a mistake or don't do it, not only will you not get 8 points, but you will also be deducted 5 points. The total score is less: 8+5= 13 (points).

Only 4 1 min, less: 80-4 1=39 (min).

So wrong: 39/ 13=3 (Dao)

Right: 10-3=7 (knife)

Comprehensive formula:10-(10 * 8-41)/(8+5) = 7 (road)