There were 36,000 hardback copies of a certain novel sold before the paperback version was issued. From the time the first paperback copy was sold until the last copy of the novel was sold, 9 times as many paperback copies as hardback copies were sold. If a total of 441,000 copies of the novel were sold in all, how many paperback copies were sold?

405,000 paperback copies were sold

Step-by-step explanation: Before the paperback version of the novel was issued for sale, there were 36000 copies of the hardback copies available.

From the time the "first paperback..." version was issued and sold out, there nine times as many paperback copies as hardback copies that were sold. That is, during the period in question, for every hardback, there was an equivalent of nine paper back.

If paperback is p, and hardback is h, what we have in effect is;

Total = p + h

However, based on the information given,  1h equals 9p. If h equals 36000, then paperback equals;

9 x 36000 = 324000

Up till the last copy of the novel was sold (441000 copies were sold), 36000 hardback copies were sold and an initial 324000 paperback were also sold.

If the total units sold was given as 441000, then the equation becomes

Total = p + h + x

Where x is the extra units sold that gave rise to the total sales

441000 = 324000 + 36000 +x

441000 =360000 + x

Subtract 360000 from both sides of the equation

81000 = x

Therefore the total paperback copies that were sold is given as

324000 + 81000 = 405,000

where is the triangle?