Please use the correct formula
show ALL work for every problem also i put 100 points into this

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

Aplot of land is shaped like a quadrilateral. fences are built on the diagonal to divide the area into 4 sections. what is vi to the nearest tenth? gv = 6.55fv = 5.84vh = 3.27vi = ?

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.