3、Buy 2 fountain pens and 3 ballpoint pens for a total of 49 yuan, with the same amount of money, you can buy 3 fountain pens and 1 ballpoint pen, then the price of 1 fountain pen is ( ) yuan.
【Analysis】Equivalent substitution. From the problem, we get: 2 pens + 3 ballpoint pens = 49 yuan $(1)$; 3 pens + 1 ballpoint pen = 49 yuan $(2)$; therefore, 9 pens + 3 ballpoint pens = 147 yuan (3); (3)-(1) gives 7 pens = 98 yuan, so, 1 pen = 14 yuan, 1 ballpoint pen = 7 yuan.