set term pngcairo size 1000, 800
set grid

f1(x) = a1*x+b1
fit f1(x) 'mnk.plot' using 1:2 via a1, b1

set output 'mnk.png'
set title "зависимтость      от t"
set xlabel "t, c"
set ylabel "ln dp1/dp(t), ед."
set key top left

set label sprintf("A = %.4g\n B = %.4g", a1, b1) at graph 0.2, 0.9 front boxed
plot 	'mnk.plot' using 1:2 notitle lc 0 pt 1 lw 2,	\
	f1(x) title "y(x)" lc rgb "red"