Answer:
3
Step-by-step explanation:
given
x *y = [tex]\frac{x+y}{x-y}[/tex]
Then the number represented by 12*(7*5)
calculate 7*5
= [tex]\frac{7+5}{7-5}[/tex] = [tex]\frac{12}{2}[/tex] = 6 , then
12*6
= [tex]\frac{12+6}{12-6}[/tex] = [tex]\frac{18}{6}[/tex] = 3