Answer
$P(offender~is~at~least~18)=\frac{6327}{7285}\approx0.8685$
Work Step by Step
The sample space: $124+619+39+290+5628+480+4+80+21=7285$ cases. That is:
$N(S)=7285$
Now, $N(offender~is~at~least~18)=619+5628+80$
$P(offender~is~at~least~18)=\frac{N(offender~is~at~least~18)}{N(S)}=\frac{6327}{7285}\approx0.8685$
