In Suits by a general contractor against the surety of a defaulting subcontractor tried to the court without a jury upon written waiver of jury trial, there being no disagreement that the measure of damages is the reasonable cost of completing the contract and the trial court finding the plaintiff’s oral and record evidence in establishing reasonable costs unreliable and so discarding all of it and basing its judg*1007merit upon expert opinion evidence as to the reasonable cost of completion. And this court upon examination of the record concluding that the findings below arc based upon substantial evidence and that they sustain the judgment, it is ordered that the judgment of the District Court be and it is hereby affirmed.