Dọc theo chiều dài, ta trồng được:

        5 . 5 : 1/4 = 22 ( khóm hoa )

dọc theo chiều rộng, ta trồng được:

       3,75 : 1/4 = 15 ( khóm hoa )

Số hoa cần được trồng dọc theo hai cạnh của vườn hoa là:

[( 22 + 15 ). 2] - 4=70(khóm hoa)

                  Đáp số: 70 khóm hoa.

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 1/5 + 4/5 : x = 0,75

1/5 + 4/5 : x = 3/4

4/5 : x = 3/4 - 1/5

4/5 : x= 11/20

x= 16/11

b) x + 1/2 = 1 - x

2x= 1 - 1/2

2x= 1/2

x= 1/4

a) 2/3 . 5/4 - 3/4 . 2/3 = 2/3 . ( 5/4 - 3/4 ) = 2/3 . 1/2 = 1/3

b) 2 . ( -3/2 )² - 7/2 = 2 . 9/4 - 7/2 = 9/2 - 7/2 = 1

 c) -3/4 . 5 3/13 - 0,75 . 36/13 = -3/4 . 5 3/13 - 3/4 . 36/13

= -3/4 ( 5 3/13 + 36/13 )

 = -3/4 . 8 = -6

A= 3/5 . 6/7 + 3/7 : 5/3 - 2/7 : 1 2/3 = 3/5 . (6/7 + 3/7 - 2/7) = 3/5

B=( -13 . 2/5 + -2/9 : 2 1/2  + 2/5 .11/9) . 2 1/2=(-13 -2/9 + 11/9) . 2/5 . 5/2=-13 + (11/9 - 2/9)= -12

C=(-4/5 + 5/7) : 2/3 + (-1/5 + 2/7) : 2/3 = -4/5 + 5/7. 3/2 + -1/5 + 2/7.3/2 = 3/2 . (-4/5 + -1/5) + (5/7 + 2/7)= 3/2 :(-1) + 1 = -2/3 + 1 = -1/2

D=4/9 : (1/15 - 2/3) + 4/9 : (1/11 - 5/22) = 4/9 : -3/5 + 4/9 : -3/22 = 4/9 . -5/3 + 4/9 . -22/3 = 4/9 . -5/3 + -22/3 = 4/9 . (-5/3 + -22/3) = 4/9 . -27/3 = -4

a)P= 2/3 - (-1/4) + 3/5 - 7/45 - (-5/9) + 1/12 + 1/35

=(2/3 + 1/4 + 1/12) + (5/9 - 7/45) + 3/5 + 1/35

=1+ 4/5+ 3/5+ 1/35 = 2 1/35

b)Q= (5 - 3/4 + 1/5) - (6 + 7/4 - 8/5) - (2 - 5/4 + 16/5)

=(5 - 6 - 2) + (-3/4 - 7/4 + 5/4) + (1/5 - 8/5 - 16/5)

=- (3 + 4/5 + 23/5)= - (3 + 11/4 + 4 3/5)

= - 8 17/20