They will save $6.
Step-by-step explanation:
For Science center, 1 ticket = $36.75/3 = $12.25
i)So for 12 tickets = $12.25 X 12 = $147
For zoo, 1 ticket = $51/4 = $12.75
ii) So for 12 tickets = $153
Difference of i and ii,
$153-$147 = $6
So, they will save $6 by choosing science center.
Hope thus helps:)