When rounding 750 to the nearest hundred, you look at the digit in the tens place, which is 5. Since 5 is greater than or equal to 5, you round up the hundreds digit to 8. Therefore, 750 should be rounded to 800.
750 should be rounded up to 800. When rounding anything equal to
or greater than 5 gets rounded up, while everything else gets
rounded down. In this case the tens place value "5" is equal to or
greater than 5, so the number rounds up.