Jiancong has 35 triangular and rectangular cards with 125 horns. How many angles do triangular cards and rectangular cards have?

Solution: according to the meaning of the question: suppose there are x triangular cards, then there are 35-x rectangular cards. Because a triangular card has three corners and a rectangular card has four corners, the equation is 3x+4 (35-x) =1253x+140-4x =125x =15 ∴ 35-x = 20.