1/5+1/2+1/4 reduce to lowest terms as indicated

Chandler was a caretaker at the state zoo. he noticed that the number of animals adopted by the zoo increased at a constant rate every year since 2010. which of the following graphs shows the slowest rate at which the animals in the zoo were adopted?

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

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