Please help me find the difference and tell me what to type, i will mark brainliest

The spotter on the ground is standing beneath the safety net. what is his distance from the base of the platform, to the nearest meter? 3 meters, 2 meters, 4 meters, 1 meter?

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?

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