Explain when a taxpayer can have standing to seek relief in federal court to mount a challenge under the Establishment Clause

What will be an ideal response?

Under Flast v. Cohen, federal taxpayers met the standing requirement to mount an Establishment Clause challenge to a federal statute providing General Treasury funds to support, inter alia, textbook purchases for religious schools. To have standing under Flast, taxpayers must show (1) a "logical link" between the plaintiff's taxpayer status "and the type of legislative enactment attacked," and (2) "a nexus" between such taxpayer status and "the precise nature of the constitutional infringement alleged."