x: 1/5=7
x = 7 x 1/5
x = 7/5
X x 2/3=9
X =9:2/3
X =27/2
1-3/7 +x=2-1/5
1-3/7 +x=9/5
4/7 +x= 9/5
x= 9/5 - 4/7
x= 43/35
4-1/3-x=2-2/5+1-3/5
4-1/3-x= 0
x= 0
B thứ nhất:
=> x = 7 x 1/5 = 7/5
=> x = 9 : 2/3 = 27/2
=> x = 4 - 1/3 - ( 2 - 2/5 + 1 - 3/5 ) = 5/3
x: 1/5=7
x=7x1/5
x=7/5
x . 2/3=9
x=9 : 2/3
x=9 x 3/2
x=27/2
1-3/7 +x=2-1/5
4/7 + x =9/5
x=9/5 - 4/7
x=43/35
4-1/3-x=2-2/5+1-3/5
11/3 - x=8/5 + 1 -3/5
11/3 - x=13/5-3/5
11/3 - x=10/5
11/3 - x=2
x=11/3 - 2
x=5/3
bài 4
đổi 85/100 kg=850 g
3/5 kg=600 g
1/2 kg=500 g
hộp 3 nặng là
850-600=250 gam
hộp 2 nặng là
850-500=350 gam
hộp 1 nặng là
600-350=250 gam
\(x:\dfrac{1}{5}=7\)
\(x=7\)\(\text{x}\dfrac{1}{5}\)
\(x=\)\(\dfrac{7}{5}\)
\(----------\)
\(x.\dfrac{2}{3}=9\)
\(x=9:\dfrac{2}{3}\)
\(x=\dfrac{27}{2}\)
\(------------\)
\(1-\dfrac{3}{7}\)\(\text{+}x=2-\dfrac{1}{5}\)
\(1-\dfrac{3}{7}\text{+}x=\dfrac{9}{5}\)
\(\dfrac{4}{7}+x=\dfrac{9}{5}\)
\(x=\dfrac{9}{5}-\dfrac{4}{7}\)
\(x=\dfrac{43}{35}\)
\(-----------\)
\(4-\dfrac{1}{3}-x=2-\dfrac{2}{5}+1-\dfrac{3}{5}\)
\(4-\dfrac{1}{3}-x=2\)
\(\dfrac{11}{3}-x=2\)
\(x=\dfrac{11}{3}-2\)
\(x=\dfrac{5}{3}\)
\(---------------\)
bài 4
Đổi \(\dfrac{85}{100}=850g;\dfrac{3}{5}kg=600g;\dfrac{1}{2}kg=500g\)
hộp thứ nhất là \((600+500)-850=250(G)\)
Hộp 2 là \(500-250=250(G)\)
hộp 3 \(850-(250\)\(+250)=\) \(350(g)\)
bài 1
x:1/5=7
x=7x1/5
x=7/5
x.2/3=9
x=9:2/3
x=27/2
1-3/7+x=2-1/5
1-3/7+x=9/5
4/7+x=9/5
9/5-4/7=43/35
4-1/3-x=2-2/5+1-3/5
11/3-x=8/5+2/5
11/3-x=2
x=11/3-2=5/3
bài 4
Đổi 3/5=60/100,1/2=50/100
hộp thứ 3 nặng là
85/100-60/100=25/100=1/4 kg
hộp thứ 2 nặng là
85/100-50/100=35/100=7/20 kg
hộp thứ 1 nặng là
85/100-(1/4+7/20)=1/4 kg
đáp số:hộp 1:1/4 kg
hộp 2:7/20 kg
hộp 3:1/4 kg
