Solve -3/4+(2/5+-4/7)

$$- \frac { 3 } { 4 } + ( \frac { 2 } { 5 } + \frac { - 4 } { 7 } )$$

Evaluate

$$-\frac{129}{140}\approx -0.921428571$$

Solution Steps

Least common multiple of 4 and 5 is 20. Convert -\frac{3}{4} and \frac{2}{5} to fractions with denominator 20.

$$-\frac{15}{20}+\frac{8}{20}+\frac{-4}{7}$$

Since -\frac{15}{20} and \frac{8}{20} have the same denominator, add them by adding their numerators.

$$\frac{-15+8}{20}+\frac{-4}{7}$$

Add -15 and 8 to get -7.

$$-\frac{7}{20}+\frac{-4}{7}$$

Fraction \frac{-4}{7} can be rewritten as -\frac{4}{7} by extracting the negative sign.

$$-\frac{7}{20}-\frac{4}{7}$$

Least common multiple of 20 and 7 is 140. Convert -\frac{7}{20} and \frac{4}{7} to fractions with denominator 140.

$$-\frac{49}{140}-\frac{80}{140}$$

Since -\frac{49}{140} and \frac{80}{140} have the same denominator, subtract them by subtracting their numerators.

$$\frac{-49-80}{140}$$

Subtract 80 from -49 to get -129.

$$-\frac{129}{140}$$

Factor

$$-\frac{129}{140} = -0.9214285714285714$$