3.
[tex]\frac{1}{3}(x:\frac{1}{15}-3) = \frac{1}{3}(x\cdot15 - 3)\\\\Odp. \ A.[/tex]
4.
[tex](3a + 4b)(4b - 3a) = (3a+4b)(-3a+4b) = -(3a)^{2}+(4b)^{2} = -9a^{2}+16b^{2}\\\\Odp. \ C.[/tex]
