Answer:
Let's define the variables:
F = number of cars recycled the first year.
S = numbers of cars recycled the second year.
Then:
"approximately 6.9 million wrecked car are recycled in two consecutive years"
This can be written as:
F + S = 6,900,000
"... were 500,000 more recycled the second year than the first year"
S - F = 500,000
Then we have a system of equations:
F + S = 6,900,000
S - F = 500,000
To solve it, the first step is to isolate one of the variables in one of the equations, let's isolate S in the second equation:
S = 500,000 + F
Now let's replace it in the first equation:
F + (500,000 + F) = 6,900,000
2*F = 6,900,000 - 500,000 = 6,400,000
F = 6,400,000/2 = 3,200,000
S = 3,200,000 + 500,000 = 3,700,000
Then in the first year there are 3,200,000 cars recycled, and in the second year there are 3,700,000 cars recycled.