2、 1)a -3

2)2X+ 10

3) 1/3X -Y

4)2/3X -7

5)3X -3Y

6)50 -6X

3、- 15 4 3/5 4,-3 1,-2

2 4 3 2 4

1 1 1 2 3

The number of seats in this row is x.

1)X -m=6

2)m=2/3X

5,1)100+2×100-25+100 ÷ 2+42 = 367 (tree)

2) 240+2× 240-25+240 ÷ 2+42 = 857 (tree)

6、a×a÷2 -π×(r×r)×h

6×6÷2 -π×(0.5×0.5)×0.2= a little difficult to calculate. Do it yourself My oral calculation is a bit poor.

7 、( 1+22%)a

( 1+22%)a×85% = 103.7% a

Profit: 3.7%

6 1 page

8、2n

2n+ 1 or 2n-1

9,3× (3-1) ÷ 2 = 3 (field)

4×(4-1)÷2=6 (field)

5×(5-1)÷2= 10 (field)

n×(n - 1)÷2

10、 17a 20a 5a+3a(n - 1)

1 1、3+3×3= 12

3+3×(7 -2)= 18

3+3×( 1 1-2)=30

No on page 62.

Page 63

Inquiry (1)704 -704

(2)352 tons

Page 64

1)- 152t

I can't square 5X square x.

3)-ab square

No on page 65.

Page 66

1、 1)-8X

2)3X

3)-7.4a

4)4/3 years

5)3ab

6)9.5 square feet

2, 1)6.5 times

2)5/2 times

I use * instead of it.

πR* -4/9πR*

=5/4πR*

I wrote it myself,