Given 9 ×A(PQR ) = 16 ×A(LMN)
A(PQR )/ A(LMN) = 16/9…………(i)
LMN ~ PQR
A(PQR )/ A(LMN) = QR2/MN2 …..(ii)
From (i) and (ii)
QR2/MN2 = 16/9
Given QR = 20
202/MN2 = 16/9
Taking square root on both sides
20/MN = 4/3
MN = 20×3/4
MN = 15
Hence the measure of MN is 15 units.