1. cálculo   psychology   calculus   botany   algebra   Hint Half-n-half Clue   2. psicología   geography   psychology   geology   zoology   Half-n-half Clue   3. álgebra   history   psychology   algebra   calculus   Half-n-half Clue   4. química   trigonometry   geography   zoology   chemistry   Half-n-half Clue   5. geografía   algebra   history   biology   geography   Half-n-half Clue   6. geología   astronomy   trigonometry   geography   geology   Half-n-half Clue   7. historia   biology   philosophy   history   geography   Half-n-half Clue