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

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

4/5:x=11/20

x=16/11

Theo chiều dài, ta trồng được:

\(5.5 : \frac{1}{4} = 22\) (khóm hoa)

Theo chiều rộng, ta trồng được:

\(3 , 75 : \frac{1}{4} = 15\) (khóm hoa)

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

\(\left[\right. \left(\right. 22 + 15 \left.\right) . 2 \left]\right. - 4 = 70\) (khóm hoa)

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) mũ 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(5 3/13+36/13)=-3/4.8=-6

a,A=[2/7(1/4-1/3)]:[2/7(1/3-2/5)]=(1/4-1/3):(1/3-2/5)=1 1/4

b) \(B = \frac{\frac{3}{4} \left(\right. \frac{1}{5} - \frac{2}{7} - \frac{1}{3} + \frac{2}{7} \left.\right)}{\frac{1}{5} \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right) - \frac{1}{3} \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right)} = \frac{\frac{3}{4} \left(\right. \frac{1}{5} - \frac{1}{3} \left.\right)}{\left(\right. \frac{1}{5} - \frac{1}{3} \left.\right) \left(\right. \frac{2}{7} + \frac{1}{3} \left.\right)} = 1 \frac{11}{52}\)

a, A=3/5.6/7+3/7.3/5-2/7.3/5=3/5.(6/7+3/5-2/7)=3/5

b, B=(-13.2/5+-2/9.2/5+2/5.11/9).5/2=(-13-2/9+11/9).2/5.5/2=-13+(11/9-2/9)=-12

c, C=(-4/5+5/7).3/2+(-1/5+2/7).3/2=(-4/5+5/7+-1/5+2/7).3/2=[(-4/5+-1/5)+(5/7+2/7)].3/2=0

d, D=4/9:(1/15-10/15)+4/9:(2/22-5/22)=4/9:-3/5+4/9:-3/22=4/9.-5/3+4/9.-22/3=4/9.(-5/3+-22/3)=4/9.-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=(5-6-2)+(-3/4-7/4+5/4)+(1/5+8/5-16/5)=-(3+5/4+7/5)=-113/20

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

b, B=(0,25-1 1/4)+(3/5+2/5)-1/8=(1/4-1-1/4)+1-1/8=-1/8