Anyone know how to solve 5.1 part (a) and (b) to get the answer? Help please

QUESTION 5 (15 marks) 5.1 A fuel-burning power plant emits nitrogen oxides at a rate of 3 g/s from a stack with an effective height of 70 m. The emission occurs on a thinly overcast night with a wind speed of 2.5 m/s. (a) Determine the downwind location at which maximum mean ground-level concentration occurs. (3 marks) (b) Determine the maximum mean ground-level concentration. (3 marks) 5.1(a) x=4400 m 5.1(b) C(4400,0,0) = 14.4 ug/m3