Answer:
 (-1)/2
Explanation:
Evaluate u + a t where u = 2, a = -5 and t = 1/2: 
u + a t = 2 - 5/2 
 
Put 2 - 5/2 over the common denominator 2. 2 - 5/2 = (2×2)/2 - 5/2: 
(2×2)/2 - 5/2 
 
2×2 = 4: 
4/2 - 5/2 
 
4/2 - 5/2 = (4 - 5)/2: 
(4 - 5)/2 
 
4 - 5 = -1: 
Answer: (-1)/2