Using L'Imparfait in hypothetical clauses introduced by si (if) + Le Conditionnel Présent

Here's a hypothetical situation in English:

-> Here you can see that if is followed by a verb in the Simple Past (won), while the second clause uses the Conditional Present (would buy).

Now look at the French:

-> Here you see that in French, si is followed by a verb in L'Imparfait (gagnait), while the second clause uses Le Conditionnel Présent (achèterait).

Here are more examples: 

Note that to express hypotheses in French, you'll use L'Imparfait after si, and Le Conditionnel Présent in the second part of the sentence.

ATTENTION: 

See other uses of L'Imparfait:
Expressing continuing action in L'Imparfait (imperfect tense)

Expressing habits or repeated actions in L'Imparfait (imperfect tense)

And to see how to conjugate in L'Imparfait: 
Conjugate regular verbs in L'Imparfait (imperfect tense) and Conjugate être in L'Imparfait (imperfect tense)