Answer:
x^2 + 5n = 4mx
=> x^2 - 4mx + 5n = 0
D=0 (since one root then roots are equal)
b^2-4ac = 0
(-4m)^2 - 4(1)(5n) = 0
16m^2 - 20n = 0
16m^2 = 20n
8m^2 = 10n
4m^2 = 5n
hope it helps.......
