A 2.4 ton truck provides an acceleration of 2.6 ft/s^2 to a 6.4 ton trailer. If the truck exerts the same force on the road while pulling a 6.9 trailer, what acceleration results?

I used the formula F=m/a
I took 2.6*6.4= 16.64, made that equal to 6.9a, and solved for a, but it wasn't right:/

1. The correct equation is F=ma, not F=m/a.
2. You're on the right track, except you forgot about the truck's mass. The total mass being accelerated includes both the truck and the trailer. So you have:

(2.4+6.4) x 2.6 = (2.4+6.9) x a

Now solve for a.