Answer:
x=7
Step-by-step explanation:
9x -5 = 58 since they are vertical angles and vertical angles are equal
9x-5 = 58
Add 5 to each side
9x-5+5 = 58+5
9x = 63
Divide each side by 9
9x/9 = 63/9
x=7
He can drink 2/5 of the 8 3/4 sodas.

The answer is 7/2 or 3 1/2 sodas.
Of course, Fred would be better off is he drank water instead of soda. :-)
The place where two equations intersect, has a certain value of y. This means that in the intersection point, the y-values of both expressions are the same, so y = y. Since y is also represented by the following equations, y = 4x and y = 2x - 2, the x-value of the intersection point is 4x = 2x - 2.
Basically put it in a calculator