Hi AL thanks for the support. The reason why we want to see d&a (depreciation and amortization) of a company's assets match capex is because d&a is an expense and if a company doesn't keep up with its maintenance expenses (capex) now, it'll cost them in the future.

To put this into perspective, if you have a car worth 20k and it loses 20% of its value each year, that means itll be worth 6.6k after 5 years (20*0.8^5), if you do absolutely nothing to it and it breaks down at year 5. But, if you maintain your car, let's say change its tires at year 3, and go to the mechanic each year then you extend the life of the car, so maybe at year 5 it's worth 20k still in terms of utility.

So, if d&a matches capex on average (actually I read d&a should match a 5 year average of capex), then you know the company is maintaining its assets.

On a final note, d&a is a relative number. It changes based on market value of the asset and you can always defer certain expenses. For instance, if you don't put heaps of maintenance into a building each year, it wouldn't make a massive difference, but it would matter over a period of 5 years, if you never end up maintaining the building.

It's a long explaination but hope it makes sense!