Solve (-3/14-8/21):20/21

$$( - \frac { 3 } { 14 } - \frac { 8 } { 21 } ) : \frac { 20 } { 21 }$$

Evaluate

$$-\frac{5}{8}=-0.625$$

Solution Steps

Least common multiple of 14 and 21 is 42. Convert -\frac{3}{14} and \frac{8}{21} to fractions with denominator 42.

$$\frac{-\frac{9}{42}-\frac{16}{42}}{\frac{20}{21}}$$

Since -\frac{9}{42} and \frac{16}{42} have the same denominator, subtract them by subtracting their numerators.

$$\frac{\frac{-9-16}{42}}{\frac{20}{21}}$$

Subtract 16 from -9 to get -25.

$$\frac{-\frac{25}{42}}{\frac{20}{21}}$$

Divide -\frac{25}{42} by \frac{20}{21} by multiplying -\frac{25}{42} by the reciprocal of \frac{20}{21}.

$$-\frac{25}{42}\times \frac{21}{20}$$

Multiply -\frac{25}{42} times \frac{21}{20} by multiplying numerator times numerator and denominator times denominator.

$$\frac{-25\times 21}{42\times 20}$$

Do the multiplications in the fraction \frac{-25\times 21}{42\times 20}.

$$\frac{-525}{840}$$

Reduce the fraction \frac{-525}{840} to lowest terms by extracting and canceling out 105.

$$-\frac{5}{8}$$

Factor

$$-\frac{5}{8} = -0.625$$