TOKYO, July 9 : Japan's Seven & i Holdings booked a 61 per cent rise in first-quarter operating profit after volatile energy markets boosted U.S. gasoline sale margins, and hiked its full-year outlook on a sharp decline in the yen.The 7-Eleven operator generated operating income of 105 billion yen over the March-May period. For the whole year, it now expects operating profit of 425 billion yen ($2.6 billion), up 5 per cent from its previous estimate and just a smidgen higher than a year earlier. • Seven & i changed its average exchange rate assumption for the full year to 157 yen to the dollar, compared to 150 yen to the dollar previously. A weaker yen boosts income repatriated from abroad.• For the second half of the year, Seven & i cut its overseas convenience store profit forecast by 24