1. Surface area (S) of a cube equals six times the square of an edge (a) of the cube.   Hint Hint       2. Density (D) is the mass (M) of a body divided by its volume (V).   Hint       3. Curved Surface area (S) of a right cone is (22/7) times the product of the radius (r) and the slant height (L).   Hint       4. Temperature in Fahrenheit (F) decreased by 32 equals 1.8 times the temperature in Celsius (C).   Hint       5. Area (A) of a rhombus is the product of the diagonals (a and b) divided by 2.   Hint       6. Hundred times the simple interest (I) equals the product of the principal (P), rate per cent per annum (r) and time in years (t).   Hint       7. Perimeter (P) of an isosceles triangle equals the length of the base (b) plus twice the length of one of the equal sides (a).   Hint