I need these explained because i domt know how to calculate the stabdard deduction.

For year 2019

b. Sybil, age 40, is single and supports her dependent parents, who live with her. Sybil also supports her grandfather, who lives in a nursing home. She has AGI of $80,000 and itemized deductions of $8,000. AGI $80,000 Less: standard deduction 18,350 Taxable income 61,650 C. Scott, age 49, is a surviving spouse. His household includes two unmarried stepsons who qualify as his dependents. He has AGI of $75,000 and itemized deductions of $10,100. AGI $75,000 Less: standard deduction 24,400 Taxable income 50,600