Subtract 9 from both sides
b = -12 - 9
simplify -12 - 9
Answer: b = -21
9 + -21 = -12 is true.
simplify brackets
simplify q + -9 to q - 9
add 9 to both sides
simplify 12 + 9 to 21
q = 21
21 + -9 = 12 is true.
Equation of a line:

m = gradient: The difference between two y points and two x points.

c = y-intercept: Where the line crosses the y-axis (x=0)
You have:

so you are missing the m and the c.
To calculate m find two y coordinates -you have (12,
<u>7</u>) and (0, <u>
1</u>)- and subtract them. Then divide this by the subtracted values of the x coordinates -you have (<u>
12</u>, 7) and (<u>
0</u>, 1)- This gives:



To calculate the c, you just see where the line crosses the y-axis. Because you have the point (0, 1), you know that when x=0, y=1. Because x=0 is on the y-axis, you can tell that the line passes through y=1. This makes your c = 1:

When you plug these values into the equation you get your answer:
Answer:
A- Overall, students are less interested in reading magazines than comics.