It's basic subtraction. you subtract 7 1/8 with 4 4/8 by turning one of the one from the seven to 8/8 and add that to 1/8 so you get 9/8. Then 6 9/8 - 4 4/8 = 2 5/8.
8 ÷ (7 - 9) * ( 4 + (-4) ) <--- notice that bolded part.
4 + (-4) = 4 - 4 = 0.
after that, you're pretty much dividing and multiplying by 0, so
whatever ÷ whatever * whatever * 0 = 0.
Answer: y=3x-7
Explanation:
The y-intercept is -7 and the line is going up by a rate of 3.