Maths for the money

I had found out that the maths for money is totally different from maths for engineering.

When doing tender or costing:

Eng. : Boss, this gadget is $1.
Boss : How do you know it's $1?
Eng. : I checked with other suppliers, and here is the other two suppliers quotations. One selling for $1.10 and the other selling for $1.15.
Boss : I want to know how they come up to this figure. You go and check the cost of the raw material, how many workers are needed to produce it, the worker's qualification, how many children they have.
Eng. : ...

When the company report the annual financial:

Boss : This year we have total project value of $100.
Eng. : (Happy) Ye.....
Boss : The profit margin is 20%, thus we loss $50.
Eng. : ??????? ($100 x 20% = -$50?????????)
Boss : However, we (the bosses) still come out with our OWN pocket money and give you all increment and bonus.
Eng. : ...

The government also use their own maths system.

S.V. : We had spent $7000 to repair the bridge.
Peo. : But last time you said, $100 for a piece of the bridge support, and there are only 18 pieces. How come it's become $7000?
S.V. : Actually there are 30 pieces of bridge support need to be repaired.
Peo. : But that only come to $3000, where is the remaining $4000?
S.V. : You see, we use $100 for each of the repair and we had employed consultant to consult us on the repair works.
Peo. : What! The consultant fees is $4000!!!!
S.V. : No! You see, $100 x 30 + consultant = $7000.
Peo. : Then the consultant fees is $4000.
S.V. : No, no, no. I repeat again $100 x 30 + consultant = $7000.
Peo. : ????????????

I think, we (the engineers and the people) need to go back to school and re-study the basic of maths again.