To simplify the expression (3/4h - 1/2g) + (7/8h - 3/4g), we need to combine like terms.
First, let's combine the terms with 'h'. We have (3/4h + 7/8h). To add these terms, we need to find a common denominator for the fractions. The least common multiple of 4 and 8 is 8, so we can rewrite the expression as (6/8h + 7/8h).
Adding these fractions, we get (6h + 7h)/8 = 13h/8.
Next, let's combine the terms with 'g'. We have (-1/2g - 3/4g). Again, we need to find a common denominator, which is 4. Rewriting the expression with a common denominator, we have (-2/4g - 3/4g).
Adding these fractions, we get (-5g/4).
Finally, combining the simplified 'h' and 'g' terms, we have (13h/8 - 5g/4).
So, the simplified expression is (13h/8 - 5g/4).