Tickets for 1 person : 4+3+12=19
People : 1+8=9
Tickets for everyone : 19x9=171
Buying all individual tickets : $1.00x171=$171
Cheapest way :
171/24=7.125
24x7=168
171-168=3
7 ticket books needed and 3 individual
$18.00x7=$126
$1.00x3=$3
$126+$3=$129