Help me please with This no need to explain

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

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?

What effect would doubling all the dimensions of a triangular pyramid have on the volume of the pyramid? explain your reasoning.