Let the planned number of parts per hour = x <span> Then the planned number of parts for the day = 8x </span><span> By finishing 4 more parts in an hour than was planned (x + 4) he fulfilled his daily task in 6 hours. </span><span> So he finished 6(x + 4) parts that day. </span><span> 6(x + 4) = 8x </span><span> 6x + 24 = 8x </span><span> 2x = 24 </span><span> x = 12 </span>