$2\mathrm{.}39$ The following data were obtained from a liquid$-$limit test on a silty clay.

Two plastic$-$limit determinations had water contents of $24\mathrm{.}2\%$ and $23\mathrm{.}5\%.$

Determine the LL$,$ PI$,$ the flow index, and the toughness index. The flow index is

the slope of the water content versus log of number of blows in the liquid$-$limit

test, and the toughness index is the PI divided by the flow index.