you can make the equation 18+16.5x=150 with the info given
to solve this you first subtract 18 from both sides
18+16.5x=150
-18 -18
16.5x=132
now divide both sides by 16.5
16.5x=132
/16.5 /16.5
x=8
therefor she can bring 8 people to the zoo (including herself)