I wonder how is the FORMULA TO CALCULATE % change in sales, Projected total assets, and Projected Current Liabilities!

I know the answer but I do not know where does the answer comes from. I NEED A FORMULA. NOT JUST A NUMBER

Here is the question and answer :

XYZ has the following financial information for 2018:

• Sales = $2M, Net Inc. = $0.4M, Div. = $0.1M
• C.A. = $0.4M, F.A. = $3.6M

C.L. = $0.2M, LTD = $1M, C.S. = $2M, R.E. = $0.8M

If 2019 sales are projected to be $2.4M, what is the amount of external financing needed, assuming XYZ is operating at full capacity, and profit margin and payout ratio remain constant?

Projected total assets = 4 X (1+0.2) = 4.8

Projected Current Liabilities = 0.2 X (1+0.2) = 0.24

% change in sales = 2.4-2/ 2 = 0.2