P17

I. A A B B B A A A A B

P18

I. A B B B A

II. C D E F A B

P19

I. B B A A B B

II. 3 4 2 1 3 1 4 2

P20

I. E G B F C D H A

II.

III. m, c, n, g, a, o, e, I, b, q, k, p, d, f, h, j, r, l

P21

I. A C D F G H

B E I J

II. B B A C A A

II. √√×√

P22

I. 9 12 5 1 6 12 7 2 8 4 3 11

II. D A C B

P23

II. ×√√×

III. 1 9=102 8=10 3 7=10

4 6=10 5 5=10 1 6=7