This is an excerpt from an article in The New York Times on January 17, 1893. What caused the situation discussed in this article?

i need the diagram.

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

the lines on a surface map are called isobars. isobars are lines of constant pressure which are measured in units called millibars. the numbers indicate the amount of air pressure, in millibars, that each line represents.