and 
use the second expression to calculate the left-hand side of the first equation:

Add 10 to both sides if this equation to get

and divide both sides by 2

this proves that x = 17, give the two initial equations
Answer:
10 didn’t eat chickens
Step-by-step explanation:
30-20=10
The system of equation that can be used to represent the number of meals sold is
x + y = 1000
5x + 10y = 3,500
Given:
Number of $5 meals sold = x
Number of $10 meals sold = y
Total number of meals = 1000
Total amount of meals = $3,500
The equations:
Quantity
x + y = 1000
Price
5x + 10y = 3,500
Therefore, the system of equation that can be used to represent the number of meals sold is
x + y = 1000
x + y = 10005x + 10y = 3,500
Learn more about equation:
brainly.com/question/15165519
Answer:

Step-by-step explanation:
Given
-12 and -15
Required
Solve the difference
The question you posted included the solution. However, the solution is incorrect;
The absolute difference is represented as:

In this case:


So, the distance is calculated as:

Open bracket


