R = [tex]\frac{18}{5}[/tex] = 3.6 and A = 2
given that R is inversely proportional to A, then
R = [tex]\frac{k}{A}[/tex] ← k is the constant of variation
To find k use the condition R = 12 when A = 1.5
k = RA = 12 × 1.5 = 18
the equation is therefore
R = [tex]\frac{18}{A}[/tex]
when A = 5, then
R = [tex]\frac{18}{5}[/tex] = 3.6
when R = 9, then
9 = [tex]\frac{18}{A}[/tex] ( multiply both sides by A )
9A = 18 ( divide both sides by 9 )
A = 2
