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Tobin is solving the equation 3 (x minus 1.25) = 11.25. His work is shown below.

3 (x minus 1.25) = 11.25. 3 x minus 3.75 = 11.25. 3 x minus 3.75 + 3.75 = 11.25 + 3.75. 3 x = 15. 3 x times 3 = 45 times 3. x = 135.

What mistake did Tobin make?

1 Answer

1 vote
he was meant to divide by 3 when the equation was 3x=15, not multiply, so he would get the answer x=5
User Arundas K V
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