The great plague started in 1665 and is believed to have originated with the yersinia pestis microorganism, which is typically transferred through the bite of an infectious flea. the last major outbreak of the bubonic plague in england killed an estimated 100,000 people.

The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people in Eurasia and peaking in Europe in the years 1346–1353.[1][2][3] Although there were several competing theories as to the cause of the Black Death, analyses of DNA from people in northern and southern Europe published in 2010 and 2011 indicate that the pathogen responsible was theYersinia pestis bacterium, resulting in several forms of plague, including the bubonic plague.[4][5]

The Black Death is thought to have originated in the arid plains of Central Asia, where it then travelled along theSilk Road, reaching Crimea by 1343.[6] From there, it was most likely carried by Oriental rat fleas living on theblack rats that were regular passengers on merchant ships. Spreading throughout the Mediterranean and Europe, the Black Death is estimated to have killed 30–60% of Europe's total population.[7] In total, the plague may have reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.[8] The world population as a whole did not recover to pre-plague levels until the 17th century.[9] The plague recurred occasionally in Europe until the 19th century.

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explanation:

doisdforiew

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13