The correct answer is $.48$ . It's given that the number $a$ is $70$% less than the positive number $b$. Therefore, $a = (1 - \dfrac{70}{100})b$, which is equivalent to $a = (1 - 0.70)b$, or $a = 0.30b$. It's also given that the number $c$ is $60$%greater than $a$ . Therefore, $c = (1 + \dfrac{60}{100})a$, which is equivalent to $c = (1 + 0.60)a$, or $c = 1.60a$. Since $a = 0.30b$, substituting $0.30b$ for $a$ in the equation $c = 1.60a$ yields $c = 1.60(0.30b$), or $c = 0.48b$. Thus, $c$ is $0.48$ times $b$. Note that $48$ and $12/25$ are examples of ways to enter a correct answer.