(-3, 3), (1, 1), (0, -2), (1, -4) (5, -1) find the domain and range and if it is a function

An airplane travels at an unknown elevation before it descends 3 miles to an elevation of 15 miles. find the elevation of the plane before its descen.

Julie was able to walk 16 km through the zoo in 6 hours. how long will it take her to walk 24 km through the zoo?

Aclassmate thinks that solving a system by graphing gives an exact answer when the lines appear to cross at a grid point, but only an approximate answer when they don't. explain why this isn't true.