It means that all values of x would make it true. Also take a look at the equation when we simplify:
4x + 7 = 1 + 4x + 6
Which simplified turns into
4x + 7 = 4x + 7
So no matter what value you put for x, it will be the same on both sides, making all values true for x.
Answer: 
Step-by-step explanation:
The formula for finding the nth term of an arithmetic sequence is given as:

first term = -15
common difference = -6 - (-15) = 9
number of terms
substituting into the formula , we have :


Answer:
Heads
Step-by-step explanation:
14x - (2x - y) - y
14x + (-1(2x - y)) - y
14x + (-1(2x) - 1(-y)) - y
14x + (-2x + y) - y
14x + 1(-2x + y) - y
14x + 1(-2x) + 1(y) - y
14x - 2x + y - y
14x - 2x
12x