2.(930-(7*50))/ 10=58

3.50/ 17

4. If the number of classes is X, it is16x+10 =18x-6, and X=8, the number of classes is 8, and the number of books is16 * 8+10 =/kloc-0.

5. Let Aunt X and Xiaohong Y (this year) do two equations 1. x = 3Y ^ 2。 (X-4)+(Y-4)=48。 Y= 14 X=42 is obtained from 1 2.

6. Let the father be X and the mother be Y: 1 in two formulas. X+Y=56 2。 (X-2)-(Y-2)=8 gives X=32 Y=24.