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:
x = 48°
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°, thus
x = 180° - (90 + 42)° = 180° - 132° = 48°
Answer:
It would be 68,70,72
Step-by-step explanation:
The sum of first and third of 3 consecutive number is 140 as 68+72 is 140.
68 is the first
72 is the third
They are all even numbers as well
Answer: the service charge per hour for premium services is $5.5
the service charge per hour for regular services is $3
Step-by-step explanation:
Let x represent the service charge per hour for premium services.
Let y represent the service charge per hour for regular services.
One customer was charged $38 after spending 2 h in premium areas and 9 regular hours. It means that
2x + 9y = 38- - - - - - - - - - - 1
Another customer spent 3 h in premium areas and 6 regular hours and was charged $34.50. It means that
3x + 6y = 34.5- - - - - - - - - - -2
We would eliminate x by multiplying equation 1 by 3 and equation 2 by 2. It becomes
6x + 27y = 114
6x + 12y = 69
Subtracting, it becomes
15y = 45
y = 45/15
y = 3
Substituting y = 3 into equation 1, it becomes
2x + 9 × 3 = 38
2x + 27 = 38
2x = 38 - 27 = 11
x = 11/2 = 5.5
