Bài giải

Chu vi mảnh vườn là :

(5,5+3,17)×2=18,5(m)

Số khóm hoa cần trồng là:

18,5:1/4=74(khóm hoa)

Vậy số khóm hoa cần trồng là 74 khóm hoa

a)1/5+4/5÷x=0,75

4/5÷x=0,75-1/5

4/5÷x=11/20

x=4/5÷11/20

x=16/11

Vậy x=16/11

b)x+1/2=1-x

x+1/2+x=1

x+x=1-1/2

2x=1/2

x=1/2÷2

×=1/4

Vậy x=1/4

a)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)-3/4×68/13-3/4×36/13

=(-1)×3/4×68/13-3/4×36/13

=3/4×(68/13-36/13)×(-1)

=3/4×32/13×(-1)

=24/13×(-1)

=-24/13

a)A=3/5×6/7+3/7÷5/3-2/7÷5/3+2/5

A=18/35+9/35-6/35

A=3/5

Vậy A=3/5

b)B=-(-13×2/5+-2/9÷5/2+2/5×11/9)×5/2

B=(-26/5+-4/45+22/45)×5/2

B=-24/5×5/2

B=-12

Vậy B=-12

c)C=-3/35÷2/3+3/35÷2/3

C=(-3/35+3/35)÷2/3

C=0÷2/3

C=0

Vậy C=0

d)D=4/9×-5/3+4/9×'22/3

D=4/9×(-5/3+-22/3)

D=4/9×(-9)

D=-4

Vậy D=-4

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

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

P=1+1+1/35

P=71/35

Vậy P=71/35

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

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

Q=(-4)-1/4+-7/5

Q=-113/20

Vậy Q=-113/20

a) A=1/3-8/15-1/7+2/3--7/15+8/7.

A=(1/3+2/3)+(-8/15+-7/15)+(-1/7+8/7)

A=1+(-1)+1

A=0+1

A=1

Vậy A=1

b)B=1/4+3/5-(1/8-2/5+5/4)

B=1/4+3/5-1/8+2/5-5/4

B=(1/4-5/4)+(3/5+2/5)-1/8

B=(-1)+1-1/8

B=0-1/8

B=-1/8

Vậy B=-1/8