Tobin is solving the equation 3(x - 1.25) = 11.25. His work is shown below: 3(x - 1.25) = 11.25 3x - 3.75 = 11.25 3x - 3.75 + 3.75 = 11.25 + 3.75 3x = 15 3x times 3 = 45 times 3 x = 135 What mistake did Tobin make? Options: - Tobin did not distribute the 3 correctly. - Tobin should have subtracted 3.75 from each side. - Tobin should have divided by 3. - Tobin did not make a mistake.

Question

MasonWilliamTurner · Answer

Tobin is solving the equation 3 ( x − 1.25 ) = 11.25 . 
 Let's analyze his steps one by one: 
 
 3 ( x − 1.25 ) = 11.25 
 Tobin distributes the 3 correctly, resulting in: 
 3 x − 3.75 = 11.25 
 
 3 x − 3.75 + 3.75 = 11.25 + 3.75 
 This simplifies to: 
 3 x = 15 
 
 3 x = 15 
 Tobin should divide both sides by 3 to solve for x , not multiply. 
 
 Instead of multiplying by 3, Tobin's next step should be: 
 x = 3 15 ​ 
 x = 5

The mistake Tobin made is in the step where he tried to multiply by 3 again instead of dividing by 3. 
 The correct choice is: Tobin should have divided by 3.

Answer (1)

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