You are an expert at summarizing long articles. Proceed to summarize the following text: 
twenty-five us firms plan to invest ## billion pesos -lrb- #.## billion dollars -rrb- here in the next three years as a sign of confidence on the philippines ' economic growth , the american chamber of commerce and industry -lrb- amcham -rrb- said thursday .
us firms to increase investment over the next three years