Atypical neutron star may have a mass equal to that of the sun but a radius of only 20 km. (a) what is the gravitational acceleration at the surface of such a star? (enter the magnitude.)

 You will have to google these constants for yourself. I am warned not to give you the references.
Givens

The given constant acceleration of the sun = 273.7 m/s^2
The Radius of the sun = 695,700 km 
Radius of the star = 20 km
acceleration on the star's surface = a1

Formula

m_test * a_sun = G * m_test * mass_sun /( r_sun)^2
. . .
m_test * a_sun. . . G* m_test* mass_star / (r_star)^2

There is a lot oc cancellation. The result is.
a_sun / a_star = (r_star)^2 / r^2 Now all you have to do is substitute

Calculations

273.7 / a _ star = (20 000)^2 / (695700 )^2
a_star = 273.7 * (695700)^2 / (20000)^2

a_star = 331176 m/s^2 which is pretty big