Given that the solution of the system of equations 2x + 5Y = 7, ax + 4Y = 6 is a solution of the equation x + y = 12, find the value of A

Given that the solution of the system of equations 2x + 5Y = 7, ax + 4Y = 6 is a solution of the equation x + y = 12, find the value of A

Simultaneous equations: 2x + 5Y = 7, x + y = 12, the solution: y = - 17 / 3, x = 53 / 3
Substituting the equation: ax + 4Y = 6, we can get: 53 / 3a-4 * 17 / 3 = 6
The solution is: a = 86 / / 53