1. The problem is to verify if the subtraction $245879 - 987542$ equals $741663$. 2. The formula for subtraction is $a - b = c$, where $a$ is the minuend, $b$ is the subtrahend, and $c$ is the difference. 3. Perform the subtraction: $245879 - 987542$. 4. Since $245879$ is less than $987542$, the result will be negative. 5. Calculate the difference ignoring the sign: $987542 - 245879 = 741663$. 6. Therefore, $245879 - 987542 = -741663$. 7. The answer your brother gave, $741663$, is the absolute value of the difference but not the correct signed result. 8. The correct answer is $-741663$.