#4
1 сорт- x
500x+(70-x)300=26000
500x+21000-300x=26000
200x=26000-21000
200x=5000:200
x=25( к)-1 сорт
70-25=45(к)
#5
t-x
4(x-1/6)-3x=2
4x-2/3-3x=2
x=2+2/3
x=2 2/3(ч)-t
4(2 2/3-1/6)=4(8/3-1/6)=32/3-2/3=10
#1
-1,5x(-x/3-2)
x=-2
-1,5*(-2)(-(-2/3-2)=3*(2/3-2)=0