Given two lines with slopes m<1 and m<2, the slope of a third line that is perpendicular to these lines would be the negative reciprocal of either slope. The negative reciprocal of m<1 is -1/m<1 and the negative reciprocal of m<2 is -1/m<2.
Since m<1 = 38 degrees, the negative reciprocal of m<1 would be -1/38.
And since m<2 = 78 degrees, the negative reciprocal of m<2 would be -1/78.
So, if m<3 is the slope of a line perpendicular to the lines with slopes m<1 and m<2, then m<3 could be either -1/38 or -1/78, depending on which slope is chosen.