Answer:
new contribution margin per unit = $275 - $137 = $138
total contribution margin = (10,000 + 4,000) x $138 = $1,932,000
total fixed costs = $690,000 + $7,000 = $697,000
operating income = $1,235,000
old operating income = $1,450,000 - $690,000 = $760,000
operating income will increase by $475,000 or 62.5%