Question

if the length of each one of the rooms is reduced by a factor of 2.1 how much less does it cost to tile all five rooms now in $.

if one is trying to tile a square room which has length L with same tile cost is given by P=cL^2 in dollars where c is a constant. suppose the cost to tile five equal sized rooms is 1957 dollars. If the length of each one of the rooms is reduced by a factor of 2.1 how much less does it cost to tile all five rooms now in $.

(I've tried the question and got the wrong answer, the correct answer is 1513.24 how ?)