Can anyone help me with this problem

1. Feb 24, 2008

Sunnie

A train slows down as it rounds a sharp horizontal turn, slowing from 84.2 km/h to 50.7 km/h in the 15 s that it takes to round the bend. The radius of the curve is 120 m. Compute the acceleration at the moment the train speed reaches 50.7 km/h. Assume that it continues to slow down at this time at the same rate.

What is the magnitude in m/s2?

What is the direction in __ ° backward (behind the radial line pointing inward)

The formulas that I have is:

Vf= Vi + AT

Rf= Ri + Vi*t + (1/2)A*T^2