( 1) 3/4 = 6: (8) = (9) ÷ 12 = 15: (20) = 24/4 ( 18).

(2) The ratio of a ratio is 5 of 2 1. If the former item is tripled, the latter item should remain unchanged.

(3) The ratio of a ratio is 65438+5/02. If the latter item is 48, the former item is (20).

2. Simplify the following ratio (writing process)

7/8: 3/4

=(7×8/8):(3×8/4)

=7:6

0.4∶2

=(0.4×5):(2×5)

=2: 10

= 1:5

Four out of seven

= (4×7): (4× 7, 7 in total)

=28:4

=7: 1

565438+34 0 = 2 3 (about 17)

3. A peanut kernel, 600 kg can squeeze out 240 kg of peanut oil. Write the weight ratio of peanut oil to peanut kernel and simplify it.

Solution 240: 600 = 2: 5

4. Prepare a pesticide, and add 2500 ml of water to every 50 ml of liquid medicine. Write the volume ratio of liquid medicine to liquid medicine and simplify it.

Dissolve 50 ml of liquid medicine to obtain 50+2500=2550 (ml).

The volume ratio of liquid medicine to liquid medicine is 50: 2550 = 1: 5 1.

Three fifths of boys and nine fifths of girls are equal. The ratio of male to female in this class is (): ().

Number of boys × 3/5 = Number of girls × 65438+9/00.

So: the number of boys = the number of girls × 10, 3 out of 9÷5.

Therefore, the number of boys = the number of girls × 3/2.

So the ratio of male to female in this class is (3): (2)

Step 6: Fill in the form.

The first line: 20,20:1

Line 2: 25: 6, 6/25

The third line: 3: 4, 3/4