Eight Digits Converter: Find the missing digits

This is a mathematical book and you must find the addition of two numbers (each one with eight digits) with the given hint of four digits and the sum of the two numbers. f.e. you have the question 1 : ( - 2 6 - - - - - ) + ( - - - - 8 6 - - ) = 86776668 and you have to find the answer 1 : 12688050 + 74088621 = 86776668