The answer is to your problem is x = 3
F(x) = 20x+300
you sub in the x values (120 hours and 100 hours) for each equation
the only one they both work for is the last one
f(x) = 20x + 300
f(100) = (20 * 100) + 300 = 2000 + 300 = 2300
f(120) = (20 * 120) + 300 = 2400 + 300 = 2700
25 out of 65 people are wearing red, if there are 65 people at the party and only 25 are wearing red you would find the percentage by dividing 65 by 25 which equals to 2.6%
i hope this is correct im not great at math but i hope this helps
D I believe I hope this helps :)