You basically add 17.50+17.50=35 and add 35+35=70, reason being is because the 35 is the 1/2 and 17.50 is the 1/4 so 70 is your answer
Let Marc's age be x. If Jeanine is twice as old as Marc, then her age will be 2x. If their ages added together are 24, then you can create the following equation:
2x + x = 24
3x = 24
x = 8
Remember that x is Marc's age. So if Marc is 8, and Jeanine is twice as old, she will be 16.
20 out of 100 read 5 or more.
20/100 = 0.2
Now multiply the total students by 0..2:
275 x 0.2 = 55
55 people read 5 or more books.