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put this solution on YOUR website!Let s=how many years there are in a score
First find the difference between 1863 and 1776
So four-score and 7 years is 87 years
So when you say "four-score", you're saying

and when you add "..and 7 years" you're adding 7 to

to get:
So this means the expression is equal to 87

Subtract 7 from both sides

Combine like terms on the right side

Divide both sides by 4 to isolate s

Divide
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Answer:
So our answer is
So this means a score is 20 years