Explanation:
Let the number of cars be c, trucks be t.
The total number of vehicles = 160,
c+t =160
Now how to show the mass of vehicles?
If there are c number of cars, with each car being 1000kg, the total weight of all the cars would be 1000c kg. With the same logic, the total weight of all the trucks would be 1400t kg.
If they all weigh 182,800kg together,
1000c + 1400t = 182 800
Looking at both of the equations now:
c+t =160
1000c + 1400t = 182 800
We have to make one of them cancel out the other, so:
1. Mutiply both sides of c+t=160 by 1000, you get
1000c + 1000t = 160 000
2. Subtract this equation from the second one above,
1000c + 1400t - (1000c + 1000t) = 182 800 - 160 000
1000c - 1000c + 1400t - 1000t = 22800
400t = 22800
t = 57
3. Substitute t= 57 into the first equation, c + t = 160,
c= 160-57 = 103
So you have 57 trucks, 103 cars.