Why x+ (y+z)= (x+y)+z

Find the sum of the first 8 terms of the following sequence. round to the nearest hundredth if necessary.

You download a video game to your computer. you have a 60-minute free trial of the game. it takes 5 1/6 minutes to set up the game 7 1/3 minutes to play each level. you want to find out how many levels you can play for free. which inequality describes the number of levels, l, you can play in 60 minutes? can you play 6 levels during your free trial? i need ,

The area (a) of a circle with a radius of r is given by the formula and its diameter (d) is given by d=2r. arrange the equations in the correct sequence to rewrite the formula for diameter in terms of the area of the circle.