What is the resultant (magnitude and direction) of these three vectors: 4.0 meters in the + x direction, meters in the -x direction and 1.0 meters in the + x direction

Select all the correct answers. which changes will increase the rate of reaction during combustion? decreasing the area of contact between the reactants adding more oxygen to the reaction removing heat from the reaction changing the reactants from solid form to powdered form lowering the exposure of the reactants to air