There were A adults, Sm male students, and Sf female students.
<span> </span>
<span>Sm = 1 + 7A </span>
<span>Sf = Sm/2 </span>
<span>A + Sm + Sf = 82 </span>
<span>A + (1 + 7A) + (1 + 7A)/2 = 82 </span>
<span>2A + 2 + 14A + 1 + 7A = 164 </span>
<span>23A + 3 = 164 </span>
<span>23A = 141 </span>
<span>A = 7 </span>
<span>The number of male students is 50. </span>
<span>The number of female students is 25.</span>
The pollution from the Industrial Revolution darkening the trees. After the trees darkened from all the soot in the air, the white moths were easier to see and more vulnerable to predators. The dark moths blended into the dark tree bark.
Answer:
Renewable Energy Resources.
Explanation:
Unlike fossil fuels which cannot be recovered when destroyed, these sources of energy can be recovered by a means of recycling . Recycling here reduces solid wastes which is one of the causes of land pollution.
Hydroelectric schemes can only be built in mountain regions where rainfall and rivers are plentiful which involves upset of aquatic ecosystem. This poses a dangerous pollution problem though.
Wind generators and solar panels are not very efficient energy producers. However, future schemes for producing solar energy via solar satellites are promising.
