Math Homework Help Vectors Grade 12?

I'm studying for my math test but i can't seem to get/understand these two questions 1)The angle between the vectors A and B is 120 degrees. The magnitude of A is 2 and the magnitude of B is 4. Determine the scalar projection of 3A+4B on B 2)The Vector R is twice as long as the vector S. The angle between... show more I'm studying for my math test but i can't seem to get/understand these two questions

1)The angle between the vectors A and B is 120 degrees. The magnitude of A is 2 and the magnitude of B is 4. Determine the scalar projection of 3A+4B on B

2)The Vector R is twice as long as the vector S. The angle between the vectors is 110 degrees.The vector projection of S on R is (2, -1, 7). Determine R

please show steps/work
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