Two points, A and B, are on an isoquant drawn with labor on the horizontal axis and

Question:

Two points, A and B, are on an isoquant drawn with labor on the horizontal axis and capital on the vertical axis. The capital-labor ratio at B is twice that at A, and the elasticity of substitution as we move from A to B is 2. What is the ratio of the MRTSL,K at A versus that at B?