Now Mabel's age is $$\frac{1}{4}$$ of her sister's age. 4 years from now, her age will be $$\frac{1}{2}$$ of her sister's age. <hr> Mabel's sister will be <input min="0" type="number" id ="imp5pg065q6_1" class="lineinput" placeholder="?" /> in 4 years.