Verified answer

HAc <-> H+ + Ac-

0.15 0 0

.15-x +x +x

(x)(x)/ .15-x ~ (using the 10% rule) = xe2/.15 = Ka

X^2/ .15 = 1.8x10e-5

x^2 = .15(1.8x10e-5)

x^2 = 2.7x10e-6

square both sides; x = 1.64x10e-3 = [H+]

Hope this helps :)