$\"\"$

The expression is $\"\"$

Place value chart for 13 and 7.

$\"\"$

\ \ line up the decimal points and draw a line above the numbers.

Annex zero to align the numbers. $\"\"$

$\"\"$

Next find the difference of the tenths digit.

The difference of the tenths digit = $\"\"$ .

$\"\"$

Next find the difference of the ones digit.

The difference of the ones digit = $\"\"$ .

$\"\"$

The difference is -20.