Straight Lines And Pair Of Straight Lines

Let \(\mathrm{A}(-1,1)\) and \(\mathrm{B}(2,3)\) be two points and \(\mathrm{P}\) be a variable point above the line \(\mathrm{AB}\) such that the area of \(\triangle \mathrm{PAB}\) is 10. If the locus of \(\mathrm{P}\) is \(\mathrm{a} x+\mathrm{by}=15\), then \(5 \mathrm{a}+2 \mathrm{~b}\) is :