A recipe says to use 4 cups of flour to make 56 cookies. What is the constant of proportionality that relates the number of cookies made, y, to the number of cups of flour used, x?

Two planes leave an airport at the same time, one flying east, the other flying west. the eastbound plane travels 20 mph slower. they are 1600 mi apart after 2 hr. find the speed of each plane.

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

Add the fractions and simplify 1/2+ 1/3