Mathematics homework help

The number of unique monthly visitors to social networking site A was 167 million visitors in 2012 and has since increased by about 33 million visitors each year. The number of unique monthly visitors to social networking site B was 32 million visitors in 2012 and has since decreased by about 17 million visitors each year. Use substitution or elimination to estimate when there were the same number of unique monthly visitors to social networking site A and social networking site B. What was that number of? visitors?