If 12 math books weigh 40 pounds, how much would 21 math books weigh?

Agrain trader buys the following amounts from three suppliers: 3,200 pounds, 5,100 pounds and 700 pounds. what is the total weight of his purchase?

Aplane is taking off from bangladesh headed to new york city. at the same time, a plane from new york city is headed to bangladesh is also taking off. the plane bound to new york city is traveling at 600 mph, while the plane traveling to bangladesh is traveling at 400 mph. how far from new york city will the two planes meet if the distance between new york city and bangladesh is 8,000 miles?

For problems 29 - 31 the graph of a quadratic function y=ax^2 + bx + c is shown. tell whether the discriminant of ax^2 + bx + c = 0 is positive, negative, or zero.