if cell c11 is 48" or less I want to add 3" to
the cell D15 examples (48+3=51) (25 + 3 =28) if cell c11 is 49 or greater
the I want to add 6" to cell d15 (50 +6 =56) ...

example in one cell (c11) I will put the number 50 in I want cell (D15) to
give me the answer 56. if in the same cell(c11) i put 28 I want to see in
cell D15 the answer 31 Can this be done and if so can I get the formula to do
so. Please