It is true. I was recently doing this in class
Answer:

Step-by-step explanation:
To write any polynomial in standard form, you look at the degree of each term. You then write each term in order of degree, from highest to lowest, left to write.
To add the polynomials you need to:
Remove parentheses

Group like terms

Add similar elements

Answer:
70.5
Step-by-step explanation:
Refer to attached image
<span>–x + 2y = 12
x + 6y = 20
------------------add
8y = 32
y = 32/8
y = 4
</span>–x + 2y = 12
–x + 2(4) = 12
-x = 12 -8
x = -4
answer: <span>(-4, 4)</span>