Let the number be 'x'.
Three times a number will then give 3x
Therefore the equation will be:
Answer:
7. 
8. l=11cm and w=7 cm
9. 
10. 
Step-by-step explanation:
Question 7.
The given expression is:

Expand the parenthesis using the distributive property:

Group similar terms:

Simplify

Divide both sides by -10

Question 8:
Let the width of the rectangle be;
The length of the rectangle is 
The perimeter is given as: 
Given that the perimeter P=36, then:
![36=2[(w+4)+w)]](https://tex.z-dn.net/?f=36%3D2%5B%28w%2B4%29%2Bw%29%5D)

Divide both sides by 2:

Subtract 4 from both sides:



The dimensions of the rectangle is: w=7 cm and l=7+4=11cm
Question 9
Let the number be x.
"5 fewer than the number" is written as 
"5 fewer than a number is at least 12" becomes

Question 10:
Let the number be x.
The quotient of a number and 3 is written as:

The quotient of a number and 3 is no more than 15 is written as;

Answer:
4±√5
EXPLAINED ANSWER:
Since the variable is a binomial and it is squared, we apply square root on both side, and apply the ± sign on the right side (since the solution of a square root can be both positive and negative), and later pass the 4 positive to the other side.
√25 can be (5)(5) or (-5)(-5)
20, you just need to substitute the x value in the equation
(-2)2-7(-2)+10=
=20
Answer it's a closed dot on positive 2 going to the left
Step-by-step explanation: