How many solutions douse this graph have⬆️

In a singing competition, there are 150 participants. at the end of each round, 40% of the participants are eliminated. how many participants are left after n rounds?

Two years ago a man was six times as old as his daughter. in 18 years he will be twice as old as his daughter. determine their present ages.

If each bricks costs and he can only buy one brick how much will it cost him to get the material to put around the outside of his garden?