How can i simplify 42/48 and show work?

You have 12 balloons to blow up for your birthday party. you blow up 1/3, and your friend blows up 5 of them. what fraction of the baloons still need blowing up

Ahovercraft takes off from a platform. its height (in meters), xx seconds after takeoff, is modeled by: h(x)=-2x^2+20x+48h(x)=−2x 2 +20x+48 what is the maximum height that the hovercraft will reach?

Y= a(x-3)squared-1 what is the value of a