The ships in Columbus's fleet included all of the following except: the Mayflower
the Santa Maria
the Niña

The Mayflower.

Explanation:

Columbus's fleet comprised of 3 ships: The Santa Maria (the largest and the flagship), the Niña, and the Pinta. On return, Columbus had only the Niña and the Pinta, as Santa Maria sunk.

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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