The expression is

Place value chart for 743 and 59.

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

 Annex one zero to align the numbers.

First find the difference on the ones digit.

Notice that it is not possible to subtract 3 from 9.

 So, 1 unit must be borrowed from tens column.

The difference of the ones digit = 13 – 9 = 4

Next find difference of the tens digit.

Notice that it is not possible to subtract 3 from 5.

 So, 1 unit must be borrowed from hundreds column.

The difference of the tens digit = 13 – 5 = 8

Next find the difference of the hundreds digit.

The difference of the hundreds digit = 6 – 0 = 6.

The difference is 684.