Evaluate 9^(5x)=9^(4x-15)

$9^{5 x} = 9^{4 x - 15}$

Create equivalent expressions in the equation that all have equal bases.

$9^{5 x} = 9^{4 x - 15}$

Since the bases are the same, then two expressions are only equal if the exponents are also equal.

$5 x = 4 x - 15$

Move all terms containing $x$ to the left side of the equation.

Subtract $4 x$ from both sides of the equation.

$5 x - 4 x = - 15$

Subtract $4 x$ from $5 x$ .

$x = - 15$