The expression is .

Place value chart for 152 and 123.

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

First find the difference of the ones digit.

Notice that it is not possible to subtract 2 ones from 3 ones.

So, 1 unit must be borrowed from tens column.

The difference of the hundredths digit = .

Next find the difference of the tens digit.

The difference of the tens digit = .

Next find the difference of the hundreds digit.

The difference of the hundreds digit = .

The difference is .