Answer:

Step-by-step explanation:
remember that,

given that,
thus substitute:

divide both sides by 4/3π:

cubic root both sides:

and we are done!
Left side: (equation) 2/x=3/90 (multiply them together by cross multiplying. 90x2 divided by 3)
=60
Altogether: 90 (right) + 60 (left) =150 seats in total
Cutting her time by 50% means reducing her time by half. Half of 45 seconds is 22.5 seconds. Therefore, to make the team, she must run a lap in 22.5 seconds.