Write 8.18*10^-3 in scientific notation

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Sophia wrote an equation to represent the revenue of a movie theater for one day. she let x represent the number of child tickets sold and y represents the nunver of adult tickets sold. if a child ticket cost $4, an adult ticket cost $6, and the total revenue for the daybwas $420, which equation could sophia use to represent the number of chikd and adult tickets that were sold?

Which pair of numbers is relatively prime? a. 105 and 128 b. 130 and 273 c. 205 and 350 d. 273 and 333