Вычислите: а) $$\frac{68^2 - 12^2}{96^2 - 16^2}$$; б) $$\frac{13^2+30\cdot13+15^2}{14\cdot40-14\cdot12}$$

а) $$\frac{68^2 - 12^2}{96^2 - 16^2} = \frac{(68 - 12)(68 + 12)}{(96 - 16)(96 + 16)} = \frac{56 * 80}{80 * 112} = \frac{56}{112} = \frac{1}{2} = 0.5$$ б) $$\frac{13^2+30\cdot13+15^2}{14\cdot40-14\cdot12} = \frac{13^2+2\cdot15\cdot13+15^2}{14(40-12)} = \frac{(13+15)^2}{14\cdot28} = \frac{28^2}{14\cdot28} = \frac{28}{14} = 2$$ Ответ: a) 0.5 б) 2