Just because 2 things are related doesn't mean they will both be changed when one thing happens. For example steak and candy, just because they are both food doesn't mean they taste the same or interact with each other.
6785 - 6496 = 289 units
289 x 13p = 3757p
3757p = £37.57
37.57 + 21.45 = £59.02
Remember that X will always be one up or down depending on if there is a - or not (if it is just an x) and one over! Hope this helps
The answer is 343 if you add all together:)))