If 1/4 of a gallon is enough for 1/3 of a room, how much paint would you need to paint four rooms?

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?

Write the standard form of an equation with (see picture below)

(-y to the power of 2 - 4y- to the power of 2 -6 y +3)