Eco-team

The student eco-team at an elementary school pledged to plant a total of 78 trees over three spring months, as the school is celebrating its 78th anniversary. In the second month, they planted half as many trees as in the first month, and in the third month, 40% more than in the first month. How many trees did the eco-team plant each month?

Final Answer:

a =  20
b =  30
c =  28

Step-by-step explanation:

$$\begin{gathered} n=78 \\ r=100\%+40\%=1+\frac{40}{100}=1.4 \\ a+(a+a/2)+r\cdot a=78 \\ a+(a+a/2)+1.4\cdot a=78 \\ 7.8a=156 \\ a=\frac{156}{7.8}=20 \\ a=20 \end{gathered}$$

$b=(a+a/2)=(20+20/2)=30$

$c=r\cdot a=1.4\cdot 20=28$

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