what is (- 2) to the 4 power in expanded form and standard form what is (- 7) to the 2nd power in expanded form and standard form

Carli has 90 apps on her phone. braylen has half the amount of apps as theiss. if carli has three timesthe amount of apps as theiss,how many apps does braylen have? let b represent the number of braylen's apps and t represent the number of theiss's apps.