When Tim says that word problems don't use mathematical notation, what does he mean

Both the red and blue line segments stretch from the center of the circle to a point on the circle. the length of the blue segment is 5. how long is the red line segment?

The lengths of two sides of a right triangle are given. find the length of the third side. round to the nearest tenth if necessary. a) y = 12/5x + 39/5 b) y = 5/12x + 5/39 c) y = 12/5x - 39/5 d) y = 5/12x - 5/39

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