The equation would be y = -(3/4)x+1
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:
The height of the triangle is
cm.
Step-by-step explanation:
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The formula for solving the area of a triangle is
where
stands for base and
stands for height.
Let's substitute 30
for the area and 10 for the base.

-------------------->>>>
Now, let's solve to find the height.

Multiply
times 

Divide both sides by 5.

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Hope this is helpful.
Answer:
X=3
Y=1
Step-by-step explanation:
In solving simultaneous equations, there are three methods, we have the elimination method, substitution method or graphical method. But for the purpose of this question, we would be using Elimination method.
5y-4x =-7 Equation 1
2y+4x=14 Equation 2
Since x has the same coefficient, it's easy to eliminate by adding up the two equations
5y+2y=7y
-4x+(+4x)=0
-7+(+14)=7
We have 7y=7
Divide both sides by 7,
y=7/7
y=1
Substituting for y in equation 2.
2(1)+4x=14
2+4x=14
4x=14-2
4x=12
x=12/4
x= 3