We want to know how much time was spent practicing the guitar in week #3. We know the time in week #1 and week #2 and the total time. So, the amount of time in week #1 and week # 2 and week #3 will equal the total time. In a math sentence with all the practice times,
week 1 + week 2 + week 3 = total
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? here represents what you don't know - and you could (if this were an algebra class) make that x. Our goal is to get the ? thing alone on one side and all the stuff on the other side.
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by getting common demonimators. The lowest common denominator, or LCD, is 12.
by combining fraction parts with fraction parts and whole numbers with whole numbers
by subtracting
by rewriting and borrowing from the whole number column and one being twelve over twelve.
by subtracting whole numbers from whole numbers and fractions from fractions
Therefore, he spent
hours practicing.