If a telescope originally costs $539.99 the tax rate is 10%. what is the total? pls someone explain how to solve these type of problems pl im not asking for a answer just explaining and possibly a example PLSS HELP ITS DUE IN 10 MINUTES

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=

Which of the following contains a variable?

Tatiana wants to give friendship bracelets to her 32 classmates. she already has 5 bracelets, and she can buy more bracelets in packages of 4. write an inequality to determine the number of packages, p, tatiana could buy to have enough bracelets.