① 18 divided by three fifths divided by two thirds = 45.

② (0 of 65438+6+0 of 65438+2) divided by 7 of 6 = 9 of 7.

③ 4-(3/4-3/8) x29 4 = 1。

P38:

(1) 2/5 of 320 = 800 (this)

There are 800 books in the library.

2 320 4/3 = 240 (Ben)

There are 240 story books in the library.

p44:

Xiao Min and Liang Xiao bought the same exercise book in the stationery store. Xiao Min bought six books and spent 1.8 yuan. Xiao Liang bought eight copies and spent * * * 2.4 yuan. The ratio of the number of exercise books bought by Xiao Min and Xiao Liang is (3): (4), and the ratio is (three quarters); The proportion of money spent is (3): (4), and the proportion is (three quarters).

(2) 3: (one eighth) = 24 (4): 8 = 0.5.

p46:

65438 in 5:6+0 in (1)6

= 5x 6:6/6:65438/6+0x 6

=5; 1

212 choose 7:8 choose 3.

= 12 7X24: 8 3 X24

= 14:9

(3) 5 in 0.125: 8

= 65438/8+0:5/8

= 65438/8+0x 8:5x 8/8

= 1:5

p49:

1. A maternity hospital had 303 newborn babies last month, and the ratio of male to female babies was 5 1: 50. How many boys and girls were born last month?

Baby boy: 303x1065438+51=153 (name)

Baby girl: 303x1065438+50in0 =150 (name)

A: Last month, the newborn boy 153 and the baby girl 150.

You must adopt me. I was exhausted from playing. Good luck.