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a) 1968 x 15 + 1968 x 84 + 1968
= 1968 x 15 + 1968 x 84 + 1968 x 1
= 1968 x (15 + 84 + 1)
= 1968 x 100 = 196800
b) 6412 + 5378 + 3582 + 4628
= (6412 + 5378) + (3582 + 4628)
= 11790 + 8210
= 20000
c) 178 x 101 - 178
= 178 x 101 - 178 x 1
= 178 x (101 - 1)
= 178 x 100
= 17800
d) 153 x 8 + 153 + 153
= 153 x 8 + 153 x 1 + 153 x 1
= 153 x (8 + 1 + 1)
= 153 x 10
= 1530
![](https://rs.olm.vn/images/avt/0.png?1311)
a: 15/x=10/15
nên x=22,5
b: 3/x=51/85
=>3/x=3/5
hay x=5
![](https://rs.olm.vn/images/avt/0.png?1311)
42+x/76=153/171
x/76=42-153/171
x/76=5922/171-153/171
x/76=5769/171
x.171=76.5769
x.71=438444
x=438444:71
x=6175,...
vay x=6175,....
de bai sai xao y ban a
![](https://rs.olm.vn/images/avt/0.png?1311)
cách 1: 153 x 99 = 15147
cách 2 : 153 x 99= 153x (100-1)
=153x100-153.1
=15300-153
=15147
mjk trươc đó
Cách 1 : 153 x 99 .
153
x
99
-------
1377
1377
--------
15147
Cách 2 : 153 x 99 = 153 x 100 - 153 = 15300 - 153 = 15147
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(1968\cdot15+1968\cdot84+1968\)
\(=1968\left(15+84+1\right)\)
\(=1968\cdot100=196800\)
b: \(6412+5378+3582+4628\)
\(=\left(6412+4628\right)+\left(5378+3582\right)\)
\(=11040+8960=20000\)
c: \(178\cdot101-178\)
\(=178\cdot101-178\cdot1\)
\(=178\left(101-1\right)=178\cdot100=17800\)
d: \(153\cdot8+153+153\)
\(=153\left(8+1+1\right)\)
\(=153\cdot10=1530\)