What made him angry?
Lencho became angry when he counted the money he received in the letter and found that only seventy pesos had reached him instead of the full amount he requested.
His anger stemmed from his unwavering confidence in God. He firmly believed that God could not have made a mistake, nor could He have denied Lencho what he had requested. Convinced that God had sent the complete amount, Lencho concluded that the post office employees had stolen the remaining money, calling them a bunch of crooks.
Explanation
The question refers to Lencho from the chapter 'A Letter to God'. Lencho's anger arises from a combination of his absolute faith in God and his distrust of the postal employees. When he receives only seventy pesos, his faith prevents him from doubting God, leading him to logically (in his mind) conclude that the post office staff must have embezzled the rest. This highlights the ironic situation where the very people who helped him are accused of theft.