3. 
HARD

Alex wants to climb up on his roof to rescue his cat. To do this, he needs to buy a ladder. Alex's house is 8 metres tall. In order for him to be able to safely climb the ladder, he has to place it so that distance from the base of the ladder to the wall is 60% of the length of the ladder. If ladders cost $3 per metre of length, how much money does Alex have to spend on a ladder?
