2) 180× 2 ÷ 20 = 18cm
3) 3600 ÷ ( 1- 1/4) × 1/4 = 1200.
4)( 1-2/3)÷( 1/ 15+ 1/ 18)
= 1/3÷ 1 1/90
=30/ 1 1 hour
5)(32-4)÷2= 14 trees
6) 10 ÷ 2 = 5m 5+2 = 7m
3. 14×7×7-3. 14×5×5
= 153.86-78.5
=75.36 square meters
7) perimeter: 3. 14×3×2= 18.84 decimeter, area: 3. 14×3×3=28.26 square decimeter.
8)300÷(700-300)=75%
9) 18÷[(7/30- 1/ 15×3)÷2]
= 18÷ 1/60
= 1080
10)40× 15%÷ 10%-40
=60-40
=20 grams
1 1)7+8= 15
24÷( 1/2-7/ 15)
=24÷ 1/30
=720 km
Line B: 720÷( 1+7/8)=384 km.
Line A: 384×7/8=336 km.