if 20 men can build a wall 66 metres long in 6 days , what length of a similar can be built by 86 men in 8 days ?
"let the required length be x metres more men , more length built ( direct proportion ) less days , less length built ( direct proportion ) men 20 : 35 days 6 : 3 : : 56 : x therefore ( 20 x 6 x x ) = ( 35 x 3 x 56 )  x = ( 35 x 3 x 56 ) / 120 = 49 hence , the required length is 49 m . answer is d"
multiply(66, divide(multiply(86, 8), multiply(20, 6)))