Answer:
x=4
Step-by-step explanation:
In order to solve for x, we must isolate x on one side of the equation.
x+3x+5=21
First, combine like terms. x and 3x are both terms with variables, and can be combined.
(x+3x) + 5=21
4x + 5=21
5 is being added to 4x. The inverse of addition is subtraction. Subtract 5 from both sides of the equation.
4x+5-5= 21-5
4x= 16
x is being multiplied by 4. The inverse of multiplication is division. Divide both sides by 4.
4x/4=16/4
x= 16/4
x=4
Let's check our solution. Plug 4 in for x and solve.
x+3x+5=21
4+3(4)+5=21
4+12+5=21
16+5=21
21=21
This solution checks out, so we know our answer is correct.
x is equal to 4, x=4.
Area of the square + area of 4 semicircles.
use s² to find the area of the square. s=8
s²=18²=324
use πr²/2
=(3.14 x 324)/2
= <span>508.9
4 semi circles right,
4 x </span><span>508.9
=</span><span>2035.8
total area = </span><span>2035.8 + 324
= </span><span>2359.8 ft</span>²<span>
</span>
Answer:
6. The number is 
7. The two numbers are
and 
Step-by-step explanation:
Question six can be re-worded to create the following expression:

Solve for x to find the number:

Question seven can be solved by first listing the constraints (assuming x is smaller than y):
- x and y are less than 20


To get the numbers, we can create a system of linear equations. First, solve for
in each expression:


Solve for
:

Solve for
:

<span>The answer is that 79 IS NOT correct because the riddle says "my ones digit is 2 LESS than my tens digit.." and 79 has 7 in tens and 9 in ones which means the ones digit is 2 MORE than the tens digit.
To solve
x has to be more than 60 and less than 100
the primes between those are 61,67,71,73,79,83, 89, 97
97 is two less in the ones than in the tens so it completes all of the requirements of the riddles therefore, 97 is the answer.</span>
Step-by-step explanation:
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