The installment fee rate of China Merchants Bank's credit card for the 24th installment is 16.32%, and that of China CITIC Bank's credit card for the 24th installment is 18.00%. Therefore, it is more cost-effective for China Merchants Bank to stage 24.

The credit card consumption of China Merchants Bank is 5800 yuan, and the installment fee rate is 16.32%, so:

Installment fee = total installment amount * installment fee rate =5800* 16.32%/24=39.44 yuan;

Principal payable in each installment = total installment amount/installment number =5800/24=24 1.67 yuan;

Total amount payable in each installment = installment fee+principal payable in each installment = 39.44+241.67 = 281.1yuan.