What properrty is shown? 4+(3+2)=4+(2+3)

If m 17 27 90 63 ** picture is attached

Which of the following is correct interpretation of the expression -4+13

The chs baseball team was on the field and the batter popped the ball up. the equation b(t)=80t-16•16+3.5 represents the height of the ball above the ground in feet as a function of time in seconds. how long will the catcher have to get in position to catch the ball before it hits the ground? round to the nearest second