#### Answer

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 %)