Over thousands of years, countries have safeguarded their citizens by doing all of the following except

Probably 1, however I can see why that would be a tiny bit confusing.

Building walls protects from incoming invaders(at least back in the day), creating armies, makes a force to go and fight to protect the people, and what was the other one? Oh yea, moving to a safer place.

Doing that would mean making invasions less likely, and making your people feel and be safer.

Hope this helps.

rain drop drop top my name is nick harris and this is my pawn shop

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