All compositions in this question are by mass.

75% of a straight-run refinery gasoline stream is mixed with 15 te/h of a 60:40 mixture of pentane and hexane to produce a blended gasoline with an improved octane rating. The composition of the straight-run stream is: butane (C₄) 5%, pentane (C₅) 10%, hexane (C₆) 25%, heptane (C₇) 60%. The blended gasoline contains 20% pentane.

Calculate

a) the flow rate of the straight-run gasoline stream which is not blended (i.e. stream 4)