Question

como se calcula -1/4 x [2/5-(-1/2)]

Answer 1

$- \frac{1}{4} .[ \frac{2}{5} -(- \frac{1}{2} )]=- \frac{1}{4} .[ \frac{2}{5} + \frac{1}{2} ]=- \frac{1}{4} .[ \frac{2.2+1.5}{10} ]= \\ \\ =- \frac{1}{4} .[ \frac{4+5}{10} ]=- \frac{1}{4} .[ \frac{9}{10} ]=- \frac{9}{40}$