91 is 10% of what number? would i get the answer of : 91 already rounded to the nearest hundredths??? these formulas are confusing me help (using proportions to solve percent)

Find the area of an equilateral triangle with a side of 6 inches

In δabc, m∠acb = 90°, cd ⊥ ab and m∠acd = 45°. find: a find cd, if bc = 3 in

A)a square brown tarp has a square green patch green in the corner the side length of the tarp is (x + 8) and the side length of the patch is x what is the area of the brown part of the tarpb)a square red placemat has a gold square in the corner the side length of the gold square is (x - 2) inches with the width of the red region is 4 in what is the area of the red part of the placemat