An engineering student answered 81 questions correctly on a 90-question test. what percent of the questions did she answer correctly?

!! 10 ! a westbound jet leaves central airport traveling 635 miles per hour. at the same time, an eastbound plane departs at 325 miles per hour. in how many hours will the planes be 1900 miles apart?

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

4+(2+x) can you me solve this problem