Last year, Mr. Engle's total income was $52,000, while his total expenses were $53,800. Use the expression where / represents total income and E represents total expenses, 12 to find the average difference between his income and expenses each month. Then explain its meaning. (Example 7)

-3.21+(-3.8)

hello. Can you explain how 0.75 was achieved? And I see how you resulted in a 1.5 as the answer however when looking at the z table the number 0.0668 correlates to -1.5, not 1.5. Can you explain? thank you again.