Respuesta :
If Trina has 3 and Randall gave her a fourth multiply 3 by 4: Randall had 12. If Randall had 12 and Selena gave him a third multiply 12 by 3: Selena had 36. If Selena had 36 and Anna gave her half multiply 36 by 2: Anna had 72. Anna had 72 brownies at the beginning :)