4a/5-9=1
a) =
b) the solution is all real numbers
c) there is no solution

  A) a = -12.5

Step-by-step explanation:

The variable, a, has been multiplied by -4/5 and then -9 added to the product. To solve for a, we undo these operations in reverse order.

To undo addition of -9, we add 9 to both sides of the equation.

  -4a/5 = 10

To undo multiplication by -4/5, we multiply the equation by its reciprocal:

  (-5/4)(-4a/5) = 10(-5/4)

 a = -50/4 = -12.5

The one solution is a=-12.5.