How do I do this and what are the answers?

Question

​Combined, there are 187 ​Asians, Africans,​ Europeans, and Americans in a village. The number of Asians exceeds the number of Africans and Europeans by 81. The difference between the number of Europeans and Americans is 12. If the number of Africans is​ doubled, their population exceeds the number of Europeans and Americans by 30. Determine the number of​ Asians, Africans,​ Europeans, and Americans in this village.

There are _​ Asians, _ ​Africans, _ ​Europeans, and _ Americans in the village.

Answer 1

Let W equal the number of Asians

Let X equal the number of Africans

Let Y equal the number of Europeans

Let Z equal the number of Americans

From the first sentence: W + X + Y + Z = 187

From the second sentence: W = X + Y + 81

From the third sentence: Y - Z = 12

From the fourth sentence: 2X = Y + Z + 30.

From these four equations we can solve for each variable.

First substitute the second equation into the first in place of W.

This gives: (X + Y + 81) + X + Y + Z + 187

Simplifying this equation: 2X + 2Y + Z = 106

Substitute the fourth equation in place of 2X gives: (Y + Z + 30) + 2Y + Z = 106

Simplifying this gives: 3Y + 2Z = 76

And the third equations says: Y - Z = 12

Multiplying this by 2 gives: 2Y - 2Z = 24

Adding this to the previous equation gives. 5Y = 76 + 24 = 100

Dividing by 5 gives Y = 20

Putting this value into equation 3 gives 20 - Z = 12. or Z = 8

Putting these values into equation 4 gives 2X = 20 + 8 + 30 or 2X = 58 so X = 29

Putting these 3 values into equation 1 gives: W + 29 + 20 + 8 = 187

Collecting and subtracting from both sides: W = 130

So there are 130 Asians, 29 Africans, 20 Europeans, and 8 Americans.

Answer 2

w represents the number of Africans

x represents the number of Asians

y represents the number of Europeans

z represents the number of Americans

w + x + y + z = 187

x = w + y + 81

y - z = 12

2x = y + z + 30

Four equations in four variables and we got an Algebra 2 system.