The coast of 16 pens is rupees 256. Find the cost of 13 pens.​

There were 816 people at a concert when a band started to play. after each song, only half the people stayed to hear the next song. how many people were left at the concert after x songs? write a function to represent this scenario.

Yesterday i ran 5 miles. today, i ran 3.7 miles. did my percent increase, decrease or is it a percent error? plz i need

X+y=-4 x-y=2 use elimination with adding and subtraction