The expression is

Annex zero to line up the columns:

Place value chart for 4.30 and 2.89.

Line up the decimal points and draw a line below the numbers.

First find the difference of the hundredths digit.

Notice that it is not possible to subtract 9 hundredths from 0 hundredths,

so 1 unit must be borrowed from tenths column.

The difference of the hundredths digit =.

Next find the difference of the tenths digit.

It is not possible to subtract 8 tenths from 2 tenths, so 1 unit must be borrowed

from ones column.

The difference of the tenths digit =.

Next find the difference of the ones digit.

The difference of the ones digit =.

The difference is.