Find the flaw with the following ""proof"" that every postage of three cents or more can be formed using just 3-cent and 4-cent stamps. basis step: we can form postage of three cents with a single 3-cent stamp and we can form postage of four cents using a single 4-cent stamp. inductive step: assume that we can form postage of j cents for all nonnegative integers j with j ≤ k using just 3-cent and 4-cent stamps. we can then form postage of k + 1 cents by replacing one 3-cent stamp with a 4-cent stamp or by replacing two 4-cent stamps by three 3-cent stamps.