Solve this please help

3-12. write each answer with a reasonable number of figures. find the absolute uncertainty and percent relative uncertainty for each answer. (a) [12.41 (±0.09) + 4.16 (±0.01)] x 7.068 2 (±0.000 4) =? (b) [3.26 (±0.10) x 8.47 (±0.05)] - 0.18 (±0.06) =? (c) 6.843 (±0.008) x 104 + [2.09 (±0.04)- 1.63 (±0.01)] =?

Asap for seven months an ice creams vendor collects data showing the number of cones sold a day (c) and the degrees above 70 degrees f the vendor finds that there is a positive linear association between c and t that is the best modeled by this equation c=3.7t+98 which statement is true? the model predicts that the average number of cones sold in a day is 3.7 the model predicts that the average number of cones sold i a day is 98 a model predicts that for each additional degree that the high temperature is above 70 degres f the total of number of cones sold increases by 3.7 the model predicts for each additional degree that the high temperature is above 70 degrees f the total number of cones sold increasingly by 98

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