The total curb weight of a truck, a car a, and a car b is 11,250 lb. the weight of car a is 15 lb less than the weight of two b cars. the truck weighs 2145 lb more than car a. what is the curb weight of each vehicle? me

The answer is: the curb weight of a truck is 5784 lb, the curb weight of a car a is 3639 lb, the curb weight of a car B is 1827 lb.
  
t - the weight of a truck
a - the weight of a car a
b - the weight of a car B

The total curb weight of the truck, the car a, and the car B is 11,250 lb:
t + a + b = 11250
The weight of car A is 15 lb less than the weight of two B cars: a + 15 = 2b
The truck weighs 2145 lb more than car A: t = a + 2145

Now, we have the system of three equations:
t + a + b = 11250
2b = a + 15          ⇒ b = (a + 15)/2
t = a + 2145

Now, substitute b and t from the second and the third equations, respectively, into the first equation:
a + 2145 + a + (a + 15)/2 = 11250
2a + (a + 15)/2 = 11250 - 2145
2a*2/2 + (a + 15)/2 = 9105
4a/2 + (a + 15)/2 = 9105
(4a + a + 15)/2 = 9105
(5a + 15)/2 = 9105
5a + 15 = 9105 * 2
5a + 15 = 18210
5a = 18210 - 15
5a = 18195
a = 18195/5
a = 3639

b = (a + 15)/2
b = (3639 + 15)/2 = 3654/2 = 1827

t = a + 2145 = 3639 + 2145 = 5784

-x+4y is the answer.