A difference is the result of a subtraction.
Call the number n.
"seven times a number": 7n
"eight more than four times the number": 4n + 8
"The difference between seven times a number and eight more than four times the number": 7n - (4n + 8)
Answer: 7n - (4n + 8)
It has 2 real solutions which are 5 and 8
You can get all the terms on one side, and then solve for x by any means:

Factor out a -2:

Factor this equation:

I will use the AC method. To use it, first multiply a and c (in ax^2 + bx +c):

Now, look for two numbers that multiply to -12 and add to -11. Obviously these numbers are -12 and 1. (-12*1 = -12 and -12+1 = -11). Now, because of rules, you set it up in a Punnett square:
4x^2 -12x
x -3
Now, we find common factors of the terms in rows:
_x_______-3__
4x| 4x^2 -12x
1 | x -3
So, you can use this to write an equivalent expression to the quadratic given:

Now, we known the factors are (solve for x):
3 and -1/4.
Answer:
c. x = -1/15
Step-by-step explanation:
5/2x - 1/3 = -1/2 [multiply the whole equation by 6 (lowest common denom)
15x - 2 = -3 [add 2 on both sides of equation
15x = -1 [divide both sides by 15 to isolate x]
x = -1/15