What caused this difference between Europe and Africa, Asia, and the Middle East during the Middle Ages?

for this case we have the following equation:

we apply distributive property to the terms within parentheses.

subtracting 2 on both sides of the equation:

although the crusades failed to capture jerusalem, they had several major impacts on western europe. they increased the authority of the king: sometimes nobles died in battle without leaving an heir in which case the king got their land. kings passed taxes to pay for the crusades.

the group i'm selecting: greeks.

a first group of greek immigrants came to the us in the 1850s. the second group came to america starting in the 1890s due to economic opportunities they didn't have back in their home caused by the hardships of ottoman rule. greek immigration was 90% male, many of them expected to work and return to greece after earning enough capital, but ultimately had to remain in the us after the greek genocide.