algebra
posted by Rachel on .
The Big Screamer Coaster carries 92 people altogether. Some of its cars carry 4 passengers, and the rest carry 6 passengers. There are three less 6passenger cars than 4passenger cars. How many 4passenger cars are there?

first, represent them as variables:
let x = fourpassenger cars
let y = sixpassenger cars
set up the equations [since two unknowns, you must have two equations]:
(1) 4x+6y=92 ==> since 92 people altogether
(2) y=x3 ==> since three less sixpassenger cars
then you can substitute the equation (2) to (1):
4x+6(x3)=92
4x+6x18=92
10x=110
x=11 fourpassenger cars
i hope i was able to help.. =)