To the extent permitted by the law governing the source of any transit funds, appropriations, contributions, grants or loans received pursuant to this article or under any other law or otherwise, such funds or moneys may also be used to pay construction costs directly and reduce expenditures to be financed from bonds of the district, and in such event, the total amount of the bonds approved by the voters may be reduced to the extent that such transit funds, appropriations, contributions, grants or loans are so applied directly to construction costs.