[poper]

$$4-10=9-15$$
$$4-10+\frac{25}{4}=9-15+\frac{25}{4}$$
$${(2-\frac{5}{2})}^2={(3-\frac{5}{2})}^2$$
$$2-\frac{5}{2}=3-\frac{5}{2}$$
$$2=3$$