P=2(A+B)
120=2(20+В)
120=40+2В
2В=120-40
2В=80
В=80/2
В=40 - длина
ответ 40
<em>14х+х-9х+2=56
15х-9х+2=56
6х+2=56
6х=56-2
6х=54
х=54:6
х=9</em>
0,9196,0,9205 ,<span>0,9107</span>
А) 0.07 / (0.4 * 3.5) = 7 / (4 * 35) = 1 / (4 * 5) = 1 / 20 = 5 / 100 = 0.05
б) (1.4 - 0.09 - 0.1) / (1-0.45) = (1.31-0.1)/(0.55) = 1.21 / 0.55 = 121 / 55 = 110 / 55 + 11/55 = 2 + 1/5 = 2.2