a. The first variable is x and the second variable is y.
b. The equations are
and 
Step-by-step explanation:
Step 1:
The first step is to define the variables. The variables can be any two symbols, letters, characters, etc.
Here let the first variable be x and the let the second variable be y.
So the variables are defined as x and y.
Step 2:
The sum of the given variables is 12.
The first variable + the second variable = 12,

The difference between the two variables is 4.
The first variable - the second variable = 4.

Step 3:
If we add both the equations we get,
and 
x = 8 and y = 4.
Answer:
1. y=5 x=8
2. x=9 y=5
3. x=12 z=4
Step-by-step explanation:
1. 4(5)+5(8)=60
2. 5(9)+3(5)=60
3. 4(12)+3(4)=60
Answer:
x=0.875
Step-by-step explanation:
3x-6=2-5x
Add 6 on both sides (6+2)
2x=8-5x
Add 5x on both sides
7x=8
Divide 7 from both sides
x=0.875
Answer:
4 people name chocolate
Step-by-step explanation:
Let's first understand the given information.
The survey shows that 40 percent of a finite number of people name chocolate as their favorite flavor of ice cream. Because the survey is reporting a percentage, then 40% means that from 100 people 40 people name chocolate, while the others name a different type of flavor.
Dividing the total of people (100) by the ones who name chocolate (40) then we have:
100/40 = 2.5
Through the above equation we are actually expressing the following:
Total people = 2.5 * (people who name chocolate flavor)
Using this equation if we have now 12 people:
12 = 2.5 * (people who name chocolate flavor)
12/2.5 = (people who name chocolate flavor)
4.8 = people who chose chocolate flavor
Because we can't have 0.8 of a person, then if we have a sample of 12 people, we will expect that 4 of them name chocolate.