3 times the sum of x and 5

Which value is not a solution of 8x^3 – 1 = 0

Astore sells two types of radios. one type sells $87 and the other for $119. if 25 were sold and the sales were $2495, how many of the $87 radios were sold a) 5 b) 20 c) 15 d)10

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?