–3/10 + 8 what is the answer huh

Which data set has a greater spread? why? set a: {38, 12, 23, 48, 55, 16, 18} set b: {44, 13, 24, 12, 56} has a greater spread because .

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.

Me, the vertices of quadrilateral coat are c(2,0), o(7,0), a(7,2) and t(2,2). prove that coat is a rectangle.