Ответ во вложении............
1)9*5=45(р.)- батьку
2)45-9=36(р.)- на ст. молодший
S = 6 <span>a</span>²<span> </span><span>= 6·(2.5)</span>²<span> </span><span>= 37.5
</span>
4.65 + y = 7.8
y = 7.8 - 4.65
y = 3.15
OTBET: y = 3.15
2-1 1/15= 14/15
14/15 : 4/9 = 126/135 : 60/135 = 2,1
2 4/15 - 2,1 = 2 40/150 - 2 10/150 = 30/150 =1/5
1/5 + 2/3 = 3/15 + 10/15 = 13/15