HI i know i am a week late but i hope this helps in some way. :)
X = Mateo Trading cards
4x-7 = Camila Treading cards
(4x-7) +x>51
4x-7+x>51
5x-7>51
5x>51+7
5x>58
x>58/5
x>11.6 = 12
Mateo can have at least 12 trading cards
Answer: <
Step-by-step explanation: The top triangle (1) has a smaller area than triangle 2.