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a) 49 x (y-21) = 441
y - 21 = 441 : 49
y - 21 = 9
y = 9 + 21
y = 30 (t/m)
b) ( y - 21 x 13 ) : 11 = 30
( y - 273 ) = 30
y = 30 + 273
y = 303
Mình viết hoa chữ Y để ko bị lẫn với dấu x nhé
49 x ( Y- 21 ) = 441
49 x Y - 49 x 21 = 441
49 x Y - 1029 =441
49 x Y =441+1029
49 x Y =1470
Y= 30
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11/15 + 8/5= Tính phân số
6/7 - 5/21=
25/4 x 16/100
7 x 2/49 =
4/3 : 2/9
5/8 : 25 =
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\(\dfrac{24}{13}:\dfrac{12}{26}+\dfrac{49}{15}:\dfrac{7}{30}\)
\(=\dfrac{24}{13}\times\dfrac{26}{12}+\dfrac{49}{15}\times\dfrac{30}{7}\)
\(=4+14\)
\(=18\)
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\(b,\frac{26}{30}:\frac{23}{15}\)
\(=\frac{26}{30}\times\frac{15}{23}\)
\(=\frac{26\times15}{30\times23}\)
\(=\frac{390}{690}\)
\(=\frac{13}{23}\)
\(a,\frac{19}{21}+\frac{14}{39}\)
\(=\frac{741}{819}+\frac{294}{819}\)
\(=\frac{1035}{819}\)
\(=\frac{115}{91}\)
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33/15 x 35/21 x 63/14 x 9/30
= 11/5 x 5/3 x 9/2 x 3/10
= 99/20
= \(\frac{33}{15}\)x \(\frac{5}{3}\)x \(\frac{9}{2}\)x \(\frac{3}{10}\)
= \(\frac{11}{3}\)x \(\frac{9}{2}\)x \(\frac{3}{10}\)
= \(\frac{33}{2}\)x \(\frac{3}{10}\)
= \(\frac{99}{20}\)
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