# A body moving in a straight line covers a distance of $14 m$ in the 5th second and 20 m in the 8th second. How much distance will it cover in the 15th second ?

$\begin{array}{1 1} zero \\ 34\;m \\ 4\;m \\2\;m \end{array}$

$S_N = u+\large\frac{a}{2} $$(2n-1) S_5= u+ \large\frac{9a}{2}-------(1) S_8= u+ \large\frac{15a}{2}-------(2) Solving (1) and (2) we get a-2 \;ms^{-2} and u-5\;ms^{-1} S_{15}=u + \large\frac{29a}{2} \quad= 5 +\large\frac{29 \times 2}{2}$$=34\;m$
The value of a and  u in above solution won't be negative.