The expression is
Place value chart for 78 and 592.
\Line up the decimal points and draw a line below the numbers.
\Annex zero to align the numbers.
\\
First find the sum of the ones digit.
\The sum of the ones digit = .
The sum is 16, so carry digits to the next column on the left.
\Next find the sum of the tens digit.
\The sum of the tens digit = .
The sum is 17, so carry digits to the next column on the left
\Next find the sum of the hundreds digit.
\The sum of the hundreds digit = .
The sum of the given expression is 670.