Let n1 and n2 be the number of photons coming out from the first and the second source of light respectively per second.
So, for the first source,
n1×λ1hc=200...(1)
And, for the second source,
n2×λ2hc=200...(2)
From equations (1) and (2), it implies that
n2n1=λ2λ1=500300⇒n2n1=53