Table: election_results_1986_4
Columns: district
incumbent
party
first_elected
result
candidates

Question: who is the incumbent with candidates being bud shuster (r) unopposed
SQL: SELECT "incumbent" FROM election_results_1986_4 WHERE "candidates" = 'Bud Shuster (R) Unopposed'

Question: who is the incumbent with candidates being tom ridge (r) 80.9% joylyn blackwell (d) 19.1%
SQL: SELECT "incumbent" FROM election_results_1986_4 WHERE "candidates" = 'Tom Ridge (R) 80.9% Joylyn Blackwell (D) 19.1%'

Question: what's district with candidates being curt weldon (r) 61.3% bill spingler (d) 38.7%
SQL: SELECT "district" FROM election_results_1986_4 WHERE "candidates" = 'Curt Weldon (R) 61.3% Bill Spingler (D) 38.7%'

Question: what's party with district being pennsylvania 21
SQL: SELECT "party" FROM election_results_1986_4 WHERE "district" = 'Pennsylvania 21'

Question: what is the maximum first elected with incumbent being gus yatron
SQL: SELECT MAX("first_elected") FROM election_results_1986_4 WHERE "incumbent" = 'Gus Yatron'

Question: what's the district with first elected being 1972
SQL: SELECT "district" FROM election_results_1986_4 WHERE "first_elected" = 1972