a)
1/5 + 3/5 = 4/5
\cdots =\frac{1+3}{5}=\frac{4}{5}
b)
1/2 + 1/3 = 5/6 ?
\cdots=\frac{3+2}{6}=\frac{5}{6}
c)
2/5 + 1/3 = 11/15 ?
\cdots=\frac{6+5}{15}=\frac{11}{15}
d)
1/4 + 2/6 = 14/24 = 7/12 ?
\cdots =\frac{3+4}{12}=\frac{7}{12}
e)
3/7 + 1/4 = 19/28 ?
\cdots=\frac{12+7}{28}=\frac{19}{28}
f)
2/7 + 2/5 = 24/35 ?
\cdots=\frac{10+14}{35}=\frac{24}{35}
g)
4/12 + 1/2 = 20/24 =10/12 = 5/6 ?
\cdots =\frac{4+6}{12}=\frac{10}{12}=\frac{5}{6}
h)
3/4 - 1/4 = 8/16 = 4/8 = 2/4 = 1/2 ?
NWw
4|2
2|2
1|
4|2
2|2
1
NWw = 2*2 = 4
\cdots\frac{3-1}{4}=\frac{2}{4}=\frac{1}{2}
i)
4/5 - 2/5 = 10/25 = 2/5 ?
\cdots = \frac{4-2}{5}=\frac{2}{5}
j)
11/13 - 7/13 = 4/13 ?
\cdots =\frac{11-7}{13}=\frac{4}{13}
k)
8/9 - 7/9 = 1/9 ?
\cdots = \frac{8-7}{9}=\frac{1}{9}
l)
5/6 - 1/3 = 9/18 ? -----------\frac{9}{18}/9 = \frac{1}{2}
NWw
6|2
3|3
1|
9|3
3|3
1|
NWW = 9 * 2 = 18
\cdots = \frac{5-2}{6}=\frac{3}{6}=\frac{1}{2}
ł)
11/12 - 1/2 = 10/24 = 5/12 ?
\cdots =\frac{11-6}{12}=\frac{5}{12}
m)
6/7 - 2/3 = 4/21 ?
\cdots = \frac{18-14}{21}=\frac{4}{21}
n)
7/9 - 1/6 = 33/54 ?------------\frac{33}{54} / 3 = \frac{11}{18}
NWw
9|3
3|3
1|
6|2
3|3
1|
NWW = 9 * 2 = 18
o)
\cdots = \frac{14-3}{18}=\frac{11}{18}
p)
13/15 - 4/6 = ???
\cdots =\frac{26-20}{30}=\frac{6}{30}=\frac{1}{5}
r)
19/20 - 4/7 = ???
\cdots =\frac{133-80}{140}=\frac{53}{140}
NWW
20|2
10|2
5 |5
1|
7|7
1|
NWW = 20 * 7 = 140 (2257=45*7=140)
s)
1/2 x 1/2 = ???
\frac{1}{2}*\frac{1}{2}=\frac{1*1}{2*2}=\frac{1}{4}
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NWW
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