What is the measure of arc OSR?

If you roll two fair dice (one black die and one white die), in how many ways can you obtain a 4 on at least one die?

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?

Afew weeks ago, vera bought 5 apples from her local farmers' market. today, she bought 4 apples. what is the percent of decrease in the number of apples bought?