See the solution as given below.
Work Step by Step
Equation for slope of a straight line is $y=mx+b$ Here $m=$ slope a) Refer the given data. we have $b=38$ $27.3=m(20)+38$ or, $m=-0.54$ Thus, $y=-0.54x+38$ ...(1) b) Refer the given data. we have $b=40$ $24.2=m(20)+40$ or, $m=-0.79$ Thus, $y=-0.79x+40$ ...(2) c) After solving the equations (1) and (2), we get $x=8, y=33.68$ Thus, (8,33.68)=(1993,33.68 %)