Solve {l}{2/7+3/8}{-4/5*3}

$$\left. \begin{array} { l } { \frac { 2 } { 7 } + \frac { 3 } { 8 } } \\ { - \frac { 4 } { 5 } \times 3 } \end{array} \right.$$

Evaluate

$$-\frac{487}{280}\approx -1.739285714$$

Solution Steps

Least common multiple of 7 and 8 is 56. Convert \frac{2}{7} and \frac{3}{8} to fractions with denominator 56.

$$\frac{16}{56}+\frac{21}{56}-\frac{4}{5}\times 3$$

Since \frac{16}{56} and \frac{21}{56} have the same denominator, add them by adding their numerators.

$$\frac{16+21}{56}-\frac{4}{5}\times 3$$

Add 16 and 21 to get 37.

$$\frac{37}{56}-\frac{4}{5}\times 3$$

Express \frac{4}{5}\times 3 as a single fraction.

$$\frac{37}{56}-\frac{4\times 3}{5}$$

Multiply 4 and 3 to get 12.

$$\frac{37}{56}-\frac{12}{5}$$

Least common multiple of 56 and 5 is 280. Convert \frac{37}{56} and \frac{12}{5} to fractions with denominator 280.

$$\frac{185}{280}-\frac{672}{280}$$

Since \frac{185}{280} and \frac{672}{280} have the same denominator, subtract them by subtracting their numerators.

$$\frac{185-672}{280}$$

Subtract 672 from 185 to get -487.

$$-\frac{487}{280}$$

Factor

$$-\frac{487}{280} = -1\frac{207}{280} = -1.7392857142857143$$