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At the given conditions, the half price is $12 less than the sale price of $75;
in other words, the half price is $75 - $12 = $63.
Hence, the regular price is twice $63, or $126. ANSWER
Solved.
You do not need use equations to solve such simple problem of the 3rd grade level of complexity.
Plain reasoning is completely enough.
Simple mental exercise/entertainment for your brain.