For the first one,
you multiply 5x and -5 to get -25.
Then you move the constant to the right and change the sign to get 3x= -21 +25.
Calculate the sum of -21+25 to get 4.
Divide both sides of the equation by 3 to get x=4/3.
So then your final answer is x=4
——
3
For the second one,
Distribute 7 through the parentheses to get 14x + 14+8=120
The you add 14+8 to get 22. Your equation should be 14x+22=120
Move the constant to the right side and change its sign to get 14x=120-22
Subtract 120-22 to get 98. Now your equation should be 14x=98
Divide both sides of the equation by 14 to get x=7.
Your finial answer for the second one should be x=7.
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I hope this made sense.
Answer: 
Step-by-step explanation:
The area of a rectangle can be calculated with the formula:

l: the length of the rectangle.
w: the width of the rectangle.
The area of the remaning wall after the mural has been painted, will be the difference of the area of the wall and the area of the mural.
Knowing that the dimensions of the wall are
by
, its area is:

As they are planning that the dimensions of the mural be
by
, its area is:

Then the area of the remaining wall after the mural has been painted is:

33/84
if you divide both top and bottom by 3 you will get your simplified answer:
11/28
About 495 CDs in a single day
3467/7=495+ small decimal