39% of a quantity is the same as 39 parts of 100 of this quantity. To find 39% of a quantity we multiply this quantity by 39 and divide by 100, or simply multiply it by 0.39 because
Since we need to multiply by 0.39 to find 39% of a quantity, if we do the inverse process of dividing an amount by 0.39, we're going to find the quantity which this amount represent 39%.
On our problem, we know that $19.8 million represent 39% of the funds, therefore, if we divide $19.8 million by 0.39 we're going to find the total amount of funds.
The total amount of donated funds is $51 million.