Mr. and Mrs. Keppner file a joint income tax return. Assume the taxable year is 2019. Compute their standard deduction assuming that Mr. Keppner is age 68, and Mrs. Keppner is age 60. Compute their standard deduction assuming that Mr. Keppner is age 70, and Mrs. Keppner is age 68. Compute their standard deduction assuming that Mr. Keppner is age 70, and Mrs. Keppner is age 68. Mrs. Keppner is legally blind.