# Spanning tree question

Hi everybody.

I want to know how to calculate a path cost between two swicthes linked by 2 links of 100 Mps.

I know that when only one link of 100 Mbps is used, the path cost used by STA is 19, but don't know how to find out the cost of two links of 100 Mps.

The book i was using answers that the path cost is 12.

Assuming that the path cost is inversely proportional to the link speed 1/12 cost does not equal 1/19 + 1/19