blowing rock railroad decided to use the high-low method and operating data from the past six months to estimate the fixed and variable components of transportation costs. the activity base used by blowing rock railroad is a measure of railroad operating activity, termed "gross-ton mile" which is the total number of tons multiplied by the miles moved. transportation cost gross ton miles jan 760,000 275,000 feb 850,000 310,000 march 600,000 200,000 april 810,000 300,000 may 680,000 240,000 june 875,000 325,000 determine the variable cost per gross-ton mile and the fixed cost. please show equations