Answer
a)51,600
b)238,500
Work Step by Step
$a_n = 43800 + (n-1)1950$, So
a) $a_5 = 43800 + (5-1)1950 = 43800 + (4)1950 = 51600$
b) $S_{5} = \frac{5(a_{5} + a_{1})}{2}=\frac{5(51600 + 43800)}{2} = 238500$ (we compute the sum $S$ using the formula for arithmetic sequence given by $S_{n} = \frac{n(a_{n} + a_{1})}{2}$)
