Solve 21/120-15/120-9/120=

$$\frac { 21 } { 120 } - \frac { 15 } { 120 } - \frac { 9 } { 120 } =$$

Evaluate

$$-\frac{1}{40}=-0.025$$

Solution Steps

Reduce the fraction \frac{21}{120} to lowest terms by extracting and canceling out 3.

$$\frac{7}{40}-\frac{15}{120}-\frac{9}{120}$$

Reduce the fraction \frac{15}{120} to lowest terms by extracting and canceling out 15.

$$\frac{7}{40}-\frac{1}{8}-\frac{9}{120}$$

Least common multiple of 40 and 8 is 40. Convert \frac{7}{40} and \frac{1}{8} to fractions with denominator 40.

$$\frac{7}{40}-\frac{5}{40}-\frac{9}{120}$$

Since \frac{7}{40} and \frac{5}{40} have the same denominator, subtract them by subtracting their numerators.

$$\frac{7-5}{40}-\frac{9}{120}$$

Subtract 5 from 7 to get 2.

$$\frac{2}{40}-\frac{9}{120}$$

Reduce the fraction \frac{2}{40} to lowest terms by extracting and canceling out 2.

$$\frac{1}{20}-\frac{9}{120}$$

Reduce the fraction \frac{9}{120} to lowest terms by extracting and canceling out 3.

$$\frac{1}{20}-\frac{3}{40}$$

Least common multiple of 20 and 40 is 40. Convert \frac{1}{20} and \frac{3}{40} to fractions with denominator 40.

$$\frac{2}{40}-\frac{3}{40}$$

Since \frac{2}{40} and \frac{3}{40} have the same denominator, subtract them by subtracting their numerators.

$$\frac{2-3}{40}$$

Subtract 3 from 2 to get -1.

$$-\frac{1}{40}$$

Factor

$$-\frac{1}{40} = -0.025$$