Help please?

a.
E = hν 
Frequency, ν = E/h
= (5.00 × 10⁻¹⁸) / (6.626 × 10⁻³⁴) Hz
= 7.54 × 10¹⁵ Hz

E = hc/λ
Wavelength, λ = hc/E
= (6.626 × 10⁻³⁴) (3.00 × 10⁸) / (5.00 × 10⁻¹⁸) m
= 3.98 × 10⁻⁸ m

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b.
c = λν
Frequency, ν = c/λ
= (3.00 × 10⁸) / (500 × 10⁻⁹) Hz
= 6.00 × 10¹⁴ Hz

Energy, E = hc/λ
= (6.626 × 10⁻³⁴) (3.00 × 10⁸) / (500 × 10⁻⁹) J
= 3.98 × 10⁻¹⁹ J

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c.
c = λν
Wavelength, λ = c/ν
= (3.00 × 10⁸) / (106.1 × 10⁶) m
= 2.83 m

Energy, E = hν
= (6.626 × 10⁻³⁴) (106.1 × 10⁶) J
= 7.03 × 10⁻²⁶ J

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d.
Energy from the 6th to 2nd energy level, E = hc/λ
= hcR [(1/n₂²) - (1/n₁²)] …… (Rydberg equation)
= (6.626 × 10⁻³⁴) (3.00 × 10⁸) (1.097 × 10⁷) [(1/2²) - (1/6²)] J
= 4.85 × 10⁻¹⁹ J

Energy from the 4th to 1st energy level, E = hc/λ
= hcR [(1/n₂²) - (1/n₁²)] …… (Rydberg equation)
= (6.626 × 10⁻³⁴) (3.00 × 10⁸) (1.097 × 10⁷) [(1/1²) - (1/4²)] J
= 2.04 × 10⁻¹⁸ J

What's nu?   c/lambda
 / / /  a little memory aide to remember the equation for frequence (Greek letter nu) = speed of light (c) divided by the wavelength (lambda)
Also use the equation  ...  E = h nu <<<  h is Plank's constant and nu is the Greek letter that looks like a v.

1.  E = hv  ///  so // v = E/h = (5x10^-18J)/(6.626x10^-34 Js)
     v = 7.55 x 10^15 s^-1  >>> units are waves/sec < freq.

    I will use L for lambda, the wavelength.

    v = c/L  
    L = c/v  =  (3x10^8 m/s) / 7.55 x 10^15 s^-1
    L = 3.97x10^-8 m

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  now you have the equations to use ... you do the rest of them