What are factors of -12 that have a sum of +1?​

The tiles below are pieces of a normal ecg tracing representing a little less than two heartbeats at a resting rate of 80 bpm. arrange the tiles in their correct order. rank from first to last. do not overlap any tiles.

Sole with work in 10 years, the average number of hours of tv watched per week by teenagers dropped from 23.9 to 21.4. find the percent of change.

Solve the following simultaneous equation by using an algebraic method (either substitution or elimination) 2x + 3y=-4 4x-y=11