Question

Find a number such that one-half of the number is 9 less than two-thirds of the number

Answer 1

Let's say, the number is "a"
thus        $\bf \cfrac{1}{2}a=\cfrac{2}{3}a-9\implies \cfrac{a}{2}=\cfrac{2a}{3}-9\implies \cfrac{a}{2}=\cfrac{2a-27}{3}$

cross-multiply and solve for "a"