Question

What is the possible range of wavelengths?

Answer 1

 λ = c / f 

λ = 3 x 10^8 / 4.29 x 10^14 
= 6.99 x 10^-7m 

To turn from m to nm, multiply by 10^9 
λ = 6.99 x 10^-7 x 10^9 = 699nm (3 sig. figs. same as data supplied) 

You do the other one the same way.