Let W = number of white cars, and Y = number of yellow cars.
There were 9 times as many white cars as yellow cars. This means that the number of white cars was 9 times more than the number of yellow cars. This can be translated by the expression:
9Y = W
The person counted 40 cars in total:
W + Y = 40
So we get the system:

In the first equation, we multiply by 9:
9W + 9Y = 360
In the second equation:
9Y= W
W-9Y = 0
Then we add the first with the second equation:
9W + 9Y + W - 9Y = 360
10 W = 360
W = 36
So He counted 36 white cars.
Hope this Helps! :)
-6, -3, 0, 1, 5
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Answer:
11/24
Step-by-step explanation:
7/8 + 11/12 + 3/4 + x = 3 km
7*3/8*3 = 21 / 24
11*2 / 12 * 2 = 22 /24
3*6 / 4*6 = 18/24
21/24 + 22/24 + 18/24 + x = 3
61 / 24 + x = 3
x = 72/24 - 61/24
x = 11 / 24
Tim has to run 11/24 of the race
Xy is the number
A) x + y = 7
B) 10y + x = 10x + y + 9
collecting terms of equation B
B) -9x + 9y = 9
multiplying A) by 9
A) 9x + 9y = 63 then adding it to equation B)
B) -9x + 9y = 9
18y = 72
y = 4
x = 3
The number is 34
The answer is B.
Hope that helps, if you need any more help, just ask : )