3. 4
4. 4x + 10 = 5x
4x -5x = 10
X = 10
4(3y^2-6y+1)-36y^2+18y=12y^2-24y+4-36y^2+18y=-24y^2-6y+4
(x + y)/8 + (x - y)/6 = 5
(x + y)/4 + (x - y)/5 = 10
первое умножаем на -2 и складываем со вторым
-(x + y)/4 - (x - y)/3 + (x + y)/4 + (x - y)/5 = -10 + 10
(x - y)(1/5 - 1/3) = 0
x = y
(x + x)/4 + (x - x)/5 = 10
2x/4 = 10
x = 20
y = 20