Find the vector v with the given magnitude and the same direction as u.
||v|| = 3
u = (4,-4)

A unit vector in the direction of u = (4, -4) is given by (4/sqrt(4^2 + (-4)^2), -4/sqrt(4^2 + (-4)^2) = (4/sqrt(32), -4/sqrt(32))

A vector in the direction of u = (4, 4) with magnitude of 3 is 3 * (4/sqrt(32), -4/sqrt(32)) = (12/sqrt(32), -12/sqrt(32))

Aand b are correctly balanced reactions. they have the same number of atoms in both sides of the reaction