How do i solve three and thirty hundredths times fifty-eight and fourteen hundredths

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

Need to increase the numbers of customers i talk to daily by 20% how many customers do i need to talk to if i talk to a average of 8 customers per hour during an 8 hour shift

: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?