4 identical books cost 13.20 What is the cost of 7 such books

What is the inverse of the function f(x)=2x+1

Which is a true statement comparing the graphs of x^2/6^2-y^2/8^2 = 1 and x^2/8^2-y^2/6^2 the foci of both graphs are the same points. the lengths of both transverse axes are the same. the directrices of = 1 are horizontal while the directrices of = 1 are vertical. the vertices of = 1 are on the y-axis while the vertices of = 1 are on the x-axis.

Simplify the expression 10/11(22z) + (a+5) -1