A bookshelf is 9 feet wide. A set of mystery books fills 1/6 of the shelf space. Each book in the set is 3/8 inch thick. How many books are in the set?

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?

Aquadratic equation in standard from is written ax^2= bx+c, where a,b and c are real numbers and a is not zero?