180× 10/( 10+ 13+ 13)
= 180× 10/36
=50 degrees
2. A rectangular vegetable field with a circumference of 42 meters and a length-width ratio of 5: 2. What is the area of this vegetable field?
The length is 42 ÷ 2× 5/(5+2) = 21× 5/7 =15m.
Width 42 ÷ 2× 2/(5+2) = 2 1× 2/7 = 6m.
Area 15×6=90 square meters.
3. Chinese teachers account for 2/5 of the total number of teachers in the school, math teachers account for 1/3 of the total number of teachers, and the rest are beautiful in sound and body. Write down the number of teachers in Chinese, Mathematics and Music.
2/5: 1/3:( 1-2/5- 1/3)=2/5: 1/3:4/9= 18: 15:20
4. Two barrels of oil, one large and one small, with a mass ratio of 7: 3. If you take 12kg from the big barrel and pour it into the small barrel, the two barrels of oil are exactly equal. How much oil is there in the two barrels? (explanation)
12× 2 ÷ (7-3 )× 3 = 24 ÷ 4× 7 = 42kg.
12×2÷(7-3)×3 = 24÷4×3 = 18kg
5. The ratio of chalk boxes of Party A and Party B is 5: 1. If you take out 12 boxes from Party A and put them in Party B, the ratio of the number of chalk boxes between Party A and Party B is 7:5, then how many boxes are there in two boxes of chalk? (explanation)
12÷5/(5+ 1)-7/(7+5)
= 12÷5/6-7/ 12
= 12÷ 1/4
=48 boxes
Find out the proportion
5 of 8 is 3 =(5/8×8):(3/8×8)= 5:3.
3.6:0.6 =6=6: 1
0 = 0.75×8 = 6 = 6: 1
4:0.25=400:25= 16: 1
1.2:2 and a quarter1=1.2: 2.25 =120: 225 = 8:15.
6/5: 3/4 = 6/5× 4/3 = 8/5 = 8: 5
0.5:25=5:250= 1:50
Eight out of nine: two = four/nine = four: nine.