12 gallons of water to fill a tank to 3/4 capacity. what is the capacity of the tank?

With alll of except for the 2 that i did already

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.

Brad earns $12.75/hr and works 40 hours a week. what is his gross annual income?