Answer:
C = 580 children.
A = 420 adult.
Explanation:
Let the number of children be C.
Let the number of adult be A.
Translating the word problem into an algebraic equation, we have;
A + C = 1000 .......equation 1
10A + 5C = 7100 .......equation 2
A = 1000 - C .......equation 3
Substituting eqn 3 into eqn 2, we have;
10(1000 - C) + 5C = 7100
10000 - 10C + 5C = 7100
10000 - 7100 = 10C - 5C
2900 = 5C
C = 2900/5
C = 580 children.
Now, to find the value of A.
From equation 3;
A = 1000 - C
A = 1000 - 580
A = 420 adult.