http://img69.imageshack.us/img69/613/spectro2.jpg

I have tried working on this question but I don't know where to even start...

okay
here r = 0.750000A = 0.7 X 10^-10 m
E1 = -Z e^2/8piE r (n=1)
now Z here is the nuclear cahrge
e is the electronic charge
E(permitivity in free space)=8.854187817... × 10−12 F·m−1
when n= 2 (first lowest transition )
r = n2 X0.7 X 10^-10 m
E2 = -Z e^2/8piE n2X r
E2-E1 will give the difference= delta E in cm^-1
DeltaE =  -Z e^2/8piE r( 1/n^2  - 1/n1^2 )
e^2/8piE r is going to be a constant
now permitted transitions are delta L= +_ 1
so four different transitions of lowest energies are
n=1 to n=2
n=2 to n=3
n=3 to n=4
then you can use the same formula for 3He+
but now Z is changed
so rest of the things are same