We know that the nearest tenth of a number is the first decimal.
The expression given: 24.583 has three decimals, we must round the first one, as the second decimal is bigger than 5,so the first decimal would be increased by 1, finally the expression 24.583 would be rounded to 24.6
This was answered in question #24217201. It's the exact same question, but you forgot to put what parts A and B are. The answers and the work are there.