Cut trees

There are 1,200 trees in the grove, of which 55 percent are deciduous, the remaining coniferous. Workers cut down 35 percent of a) trees, b) deciduous trees, and c) coniferous trees. How many trees now have this grove?

Correct answer:

a =  780
b =  969
c =  1011

Step-by-step explanation:

$$\begin{gathered} n=1200 \\ l=\frac{55}{100}\cdot n=\frac{55}{100}\cdot 1200=\frac{55\cdot 1200}{100}=\frac{66000}{100}=660 \\ i=n-l=1200-660=540 \\ q=35\%=\frac{35}{100}=\frac{7}{20}=0.35 \\ a=n-q\cdot n=1200-\frac{7}{20}\cdot 1200=780 \end{gathered}$$

$b=n-q\cdot l=1200-\frac{7}{20}\cdot 660=969$

$c=n-q\cdot i=1200-\frac{7}{20}\cdot 540=1011$

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