if rounding to the nearest tenth then the number in the hundredth determines what to do - if the number in hundredths is '5 and above, give it a shove'
meaning in this case the 7 bumps the 9 up by one; but a nine will carry over and bump the number in the ones place up by one
we know we’re rounding to the nearest tenth, so the hundredths place will come in handy.
Since there is a 7 in the hundredths place, we know we’re going to round up, but we have a 9 in the tenths place, so it would become a ‘10’, which is just going into the next whole number, which is 28.