Matthew S. answered 02/28/20
PhD in Mathematics with extensive experience teaching Calculus
<u,v> means dot product of u and v
Orthogonal projection of u onto v is <u,v>/<v,v> times v.
<u,v> = 3*4 + 62 = 48 and <v,v> = 42 + 62 = 52, so <u,v>/<v,v> = 48/52 = 12/13. Therefore projection of u onto v is 12/13 * (4, 6). Answer d) is the right answer.