 Hi and welcome to the session, let's work out the following question. The question says in the given figure find the length of D e. If A e is 15 centimeter, D b is 4 centimeter and C d is 9 centimeter. Now this is a figure given to us. So let us see the solution to this question. We have A e 15 centimeter, D b 4 centimeter that is, this is 15 centimeter, this is 4 centimeter, C d is 9 centimeter and D e is something that we have to determine. First of all, let A d be equal to x. Therefore, D e will be A e minus A d that is 15 minus x. Now we know that C d into B d is equal to A d into D e. This implies 9 into 4 is equal to x into 15 minus x. This implies 36 is equal to 15x minus x square. This implies x square minus 15x plus 36 is equal to 0. This implies x square minus 12x minus 3x plus 36 is equal to 0. This implies x into x minus 12 minus 3 into x minus 12 is equal to 0. This implies x minus 3 into x minus 12 is equal to 0. This implies either x minus 12 is equal to 0 or x minus 3 is equal to 0. This implies that x is equal to 12 and this implies that x is equal to 3. Therefore, D e will be 15 minus 12 that is 3 centimeter or D e will be 15 minus 3 that is 12 centimeter. So this is our answer to this question. I hope that you understood the solution and enjoyed the session. Have a good day.