An arrangement of billiard balls has 5 balls in the first row and 16 rows in all. in each successive row one ball is added. what is the explicit rule for this situation, and how many balls will be in the 16th row?

Gregory draws a scale drawing of his room. the scale that he uses is 1 cm : 4 ft. on his drawing, the room is 3 centimeters long. which equation can be used to find the actual length of gregory's room?

Nick has box brads. he uses 4 brads for the first project. nick let’s b represent the original number of brads and finds that for the second project, the number of brads he uses is 8 more than half the difference of b and 4. write an expression to represent the number of brads he uses for the second project.

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?