An average a day

Forest workers planted 96 trees on Monday, 120 on Tuesday, and 61 on Wednesday. How many trees did she plant on the last day of Thursday if she planted an average of 105 trees a day?

Correct answer:

x =  143

Step-by-step explanation:

$$\begin{gathered} \frac{96+120+61+x}{4}=105 \\ 96+120+61+x=105\cdot 4 \\ x=143 \\ x=\frac{143}{1}=143 \\ x=143 \end{gathered}$$

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