If 97% came from domestic sources then 3% came from foreign sources. This means that $450,000 is 3/100 of the total amount. You need to divide 450,000 by 3 to get 1/100 (1%) of the total amount, then multiply that number by 100 to give you the sum of 100/100 (100%) of the company's revenues:
450,000/3=150,000×100= $15,000,000
So, the company made $15,000,000 last year