( 18+ 10)? 2=56 cm

15+12+11+20 = 58 (m)

2, 54 decimeters; 16m; 16cm

3、40? 4= 160 (m)

4、( 14+8)? 2=44 cm

5、 12? 4=3

( 12+3)? 2=30 cm

6、 (5? 3+5)? 2 = 40 (decimeter)

7. Square circumference: 6? 4 = 24 (decimeter)

Perimeter of other figures: (9-6+6)? 2 = 18 (cm)