A vector

Question

A = (5.40i − 2.10j) m and a vector B = (1.00i + Byj) m
are related by a scalar quantity such that
A = sB.
Determine the value of the y component of the vector B.

Answer 1

since 5.40i = 5.4 * 1.0i
A = 5.40 B
So now you know how to find By

Answer 2

Ax/Bx = Ay/By
5.4/1 = -2.1 /By
By = -21./5.4

Answer 3

Thank you both