Question

(4/8 + 2/7 - 3/5 ) / 8/4

Answer 1

8,7,5 / 2
4,7,5 / 2     m.c.m = 2³ × 5 × 7 = 280
2,7,5 / 2
1,7,5 / 5
1,7,1 / 7
1,1,1

$\dfrac{\left( \dfrac{4}{8} + \dfrac{2}{7} - \dfrac{3}{5}\right) }{ \dfrac{8}{4} } \\ \\ \\ \dfrac{\left( \dfrac{140}{280} + \dfrac{80}{280}- \dfrac{168}{280}\right) }{2} \\ \\ \\ \dfrac{\left( \dfrac{140+80-168}{280}\right)}{2} \\ \\ \\ \dfrac{ \dfrac{52}{280} }{\dfrac{2}{1}} = \cfrac{52*1}{280*2} = \cfrac{52:4}{560:4} =\boxed{\bf \frac{13}{140} }\to Respuesta$

Saludos desde Venezuela