3/4 x -18 = 1/4 x -4
subtract 1/4 x from each side
3/4 x -1/4 x -18 = 1/4 x- 1/4 x -4
2/4 x - 18 = -4
add 18 to each side
1/2 x -18 + 18 = -4 + 18
1/2 x =14
multiply by 2 on each side
2* 1/2 x = 14 * 2
x =28
An example of unit price in germany is the electricity