You can do subtract half of 4 which is 2 and multiply by 2 by 7 so it will be 2x14 which is the same thing as 7x4<span />
Add all the sides up to equal 30 in an equation because you are given the perimeter. The perimeter is the length around a two dimensional shape. This means the perimeter is the length of all the side lengths added together.
(x) + (2x + 2) + (13) = 30
Combine like terms.
3x + 15 = 30
Subtract 15 from both sides.
3x = 15
Divide both sides by 3.

For a better understanding of the solution given here please find the attached file which has the relevant diagram.
To answer this question we will have to make use of <u>the Isosceles Triangle Theorem</u> which states that the perpendicular bisector of the base of an isosceles triangle is also the angle bisector of the vertex angle. Thus, as a corollary we know that is EF is the angle bisector of the vertex angle ∠E, then, EF is the perpendicular bisector of the of the base DK.
Please follow the diagram of a complete understanding of the logic and the solution.
As EF is the angle bisector as given in the question, thus we will have:
.
Also, from the Theorem we know that KF will be half of DK and thus, KF will be:
centimeters.
Likewise, from the same theorem we have: 
First you have to canceled out the fours from both side 4x/4-12/4 so x=3 then you do the same thing to the 7x-18
4x-12.
4x/4-12/4. So x=3
The fours cancelled out
7x-18
7x/7-18/7. So x= 2 4/7
The sevens cancelled out
Answer:
The temperature of the chemical solution after t hours is 
Step-by-step explanation:
Given that the initial temperature of the chemical solution,
.
The rate of decreasing temperature, 
So, after t hours, the temperature of the chemical solution will decrease by
.
So, the temperature of the chemical solution after t hours,

Hence, the temperature of the chemical solution after t hours is
.