1.

Evaluate each of the following:i)  \(\frac{2}{3}-\frac{3}{5}\)ii) \(\frac{-4}{7}-\frac{2}{-3}\)iii)  \(\frac{4}{7}-\frac{-5}{-7}\)iv) \(-2-\frac{5}{9}\)v) \(\frac{-3}{-8}-\frac{-2}{7}\)vi) \(\frac{5}{63}-\frac{-8}{21}\)vii) \(\frac{7}{24}-\frac{19}{36}\)

Answer»

i) 2/3 – 3/5

\(=\frac{(2\times5-3\times3)}{15}\\=\frac{1}{15}\)

ii) (-4/7) – (2/-3)

= (2/-3) = (-2/3)  (convert the denominator to positive number by multiplying by -1)
= -4/7 – (-2/3)

\(=\frac{(-4\times3-(-2\times7))}{21}\\=\frac{(-12+14)}{21}\\=\frac{2}{21}\)  

iii)  4/7 - -5/-7

 convert the denominator to positive number by multiplying by -1
= (-5/-7) = (5/7)
= 4/7 – 5/7

\(=\frac{(4-5)}{7}\\=\frac{-1}{7}\)

iv)  (-2) – (5/9)

\(=\frac{-2}{1}-\frac{5}{9}\\=\frac{(-2\times9-5\times1)}{9}\\=\frac{(-18-5)}{9}\\=\frac{-23}{9}\)

v) (-3/-8) - (-2/7)
 convert the denominator to positive number by multiplying by -1
(-3/-8) = 3/8
= 3/8 – (-2/7)
\(=\frac{(3\times7-(-2\times8))}{56}\\=\frac{(21+16)}{56}\\=\frac{37}{56}\)

vi) 5/63 - (-8/21)
\(=\frac{(5\times1-(-8\times3))}{63}\\=\frac{(5+24)}{63}\\=\frac{29}{63}\)

vii) 7/24 – 19/36

\(=\frac{(7\times3-19\times2)}{72}\\=\frac{(21-38)}{72}\\=\frac{-17}{72}\)



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