-7a-4b Find the answer precalculus

Subscriptions to a popular fashion magazine have gone down by a consistent percentage each year and can be modeled by the function y = 42,000(0.96)t. what does the value 42,000 represent in the function?

Which radical expression is a rational number? a. √ 360 b. √ 644 c. √ 225 d. √ 122

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)