Which of these is a linear equation?

The cost of an adult ticket is $12.50

Step-by-step explanation:

The given information are;

The cost of two adult tickets and three children tickets = $43.00

The cost of one adult ticket and one child ticket = $18.50

Whereby the cost of an adult ticket is represented by x and the cost of a child's ticket is represented by y, we get the following two simultaneous equations;

2·x + 3·y = 43.00...(1)

x + y = 18.5...(2)

(ii) Multiplying equation (2) by 2 and subtracting the result from equation (1) gives;

2·x + 3·y - 2×(x + y) = 43 - 2×18.5 = 6

2·x - 2·x + 3·y - 2·y = 0 + y = 6

∴ y = 6

The cost of each the children ticket = $6.00

From equation (2), where y = 6, we get;

x + y = 18.5

∴ x + 6 = 18.5

x = 18.5 - 6 = 12.5

The cost of an adult ticket, x = $12.50.