20 Answer: a₁ = 4
<u>Step-by-step explanation:</u>

21 Answer: n = 13
<u>Step-by-step explanation:</u>

22 Answer: n = 5
<u>Step-by-step explanation:</u>

Answer: 9x-3x and 5x+x
Step-by-step explanation:
1. Brianna's thinking is incorrect because of course, when x is 0, the expression will equal whatever value isn't an x term. To find equivalent expression, you actually need to find which expressions have the same amount of x terms and the same value.
2. Expressions A and C are equivalent.
3. Expression A can be simplified, as you can do 9x - 3x = 6x, so your final expression would be 6x - 4. Expression C can also be simplified with 5x + x = 6x, which can then also be written as 6x - 4. This means both expressions have the same amount of x terms, and the same value, so they are equivalent.
He uses 5/8 tanks of gas in one week.
In 5 he will use, 5/8 *5 = 25/8 in 5 weeks
This can be simplified too:
3.125 tanks of gas
The answer is, 25/8 tanks of gas or 3.125 tanks of gas
Answer
That doesnt make a complete triangle.
Step-by-step explanation:
The hypotenuse cannot be the same length as the other two sides of the triangle.