4/3-(2/5+3/ 10) 5/7+ 1/4-9/ 14 3/4+3/6-5/8

=40/30-( 12/30+9/30) =20/28+7/28- 18/28 = 18/24+ 12/24 - 15/24

= 19/30 =9/28 =30/24=5/8

5/9+(3/4- 1/2) 1/ 10+3/8-2/5 3/5-(2/ 15+ 1/3)

=20/36+(27/36- 18/36 =4/40+ 15/40- 16/40 = 19/ 15-(2/ 15=5/ 15)

=29/36 =3/40 =2/ 15

2.

1- 1/4-3/8

=8/8-2/8-3/8

= 3/8m

3.

1- 1/5-3/ 10

= 10/ 10-2/ 10-3/ 10

= 1/2

4.

( 1)4/25+ 19/ 100= 16/ 100+ 19/ 100=7/20

(2)7/25+9/50+ 19/ 100=28/ 100+ 18/ 100+ 19/ 100= 13/20

raise a question

(1) How much is the middle and high mountain area more than the low hills?

7/25- 19/ 100=9/ 100

(2) What is the * * * area above 2000m above sea level?

9/50+ 19/ 100=37/ 100