Question

multiply the sum of 6/7 and -13/21 by their difference​

Answer 1

Here is your answer - -

6/7 + - 13/21

LCM= 21

6/7× 3/3 = 18/21

Sum-

18/21+13/21 = 31/21

Difference-

18/21-13/21 = 5/21

Multiplication

31/21× 5/21 = 155 /441

Answer 2

sum of 6/7 + (-13/21) =

$\frac{6}{7} - \frac{13}{21}$

now taking LCM

$\frac{6 \times 3 - 13}{21} = \frac{18 - 13}{21} = \frac{5}{21}$

now their difference

$\frac{6}{7} - ( \frac{ - 13}{21} ) = \frac{6}{7} + \ \frac{13}{21}$

taking LCM

$\frac{6 \times 3 + 13}{21} = \frac{31}{21}$

now multiplying

$\frac{5}{21} \times \frac{31}{21} = \frac{155}{441} = 0.359$
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