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! :)
Answer:
75°
Step-by-step explanation:
There are 180° in a triangle, so using the ratios and the 180° setup an equation. Solve for x.
5x + 9x + 10x = 180
24x = 180
24x/24 = 180/24
x = 7.5
To find the largest angle measure, use 10x since 10 is bigger than 5 and 9.
10x
10(7.5)
75°
Write an equation system based on the problem
For an instance, e stands for the price of a carton of eggs, and b stands for the price of a loaf of bread
"Kate bought 3 cartons of eggs and 5 loaves of bread for $30.07" could be written as 3e + 5b = 30.07 (first equation)
"Melissa bought 2 cartons of eggs and 2 loaves of bread for $14.74" could be written as 2e + 2b = 14.74 (second equation)
Solve the equation system using elimination method
Eliminate b to find e. To eliminate b, we should equalize the coefficient of b.
3e + 5b = 30.07 (multiplied by 2)
2e + 2b = 14.74 (multiplied by 5)
-------------------------------------------
6e + 10b = 60.14
10e + 10b = 73.70
------------------------- - (substract)
-4e = -13.56
e = -13.56/-4
e = 3.39
The price for a carton of eggs is $3.39
Answer:
Dimensions: 
Perimiter: 
Minimum perimeter: [16,16]
Step-by-step explanation:
This is a problem of optimization with constraints.
We can define the rectangle with two sides of size "a" and two sides of size "b".
The area of the rectangle can be defined then as:

This is the constraint.
To simplify and as we have only one constraint and two variables, we can express a in function of b as:

The function we want to optimize is the diameter.
We can express the diameter as:

To optimize we can derive the function and equal to zero.

The minimum perimiter happens when both sides are of size 16 (a square).
Answer:
Question is not clear please post question clearly lots of question marks.