1)
а) 6a-3b/8a-4b = 3(2a-b)/4(2a-b) = 3/4
б) 12a²-16a/3a²-4a = 4a(3a-4)/a(3a-4) = 4
в) a²-b²/a-b = (a+b)(a-b)/(a-b) = a+b
г) xy+x²y/xy-xy² = xy(1+x)/xy(1-y) = 1/(1-y)

2)
а) 6ab-9b²/4²-9b² = 3b(2a-3b)/(2+3b)(2-3b) = 3b/(2+3b)
б) 4c²-25x²/4c²+20cx+25x² = (2c-5x)(2c+5x)/(2c+5x)² = (2c-5x)/(2c+5x)
в) 2x³y-8xy³/2xy²-x²y = 2xy(x²-4y²)/y(2x-x²) = 2x(x+2y)

3)
а) 3a+12b/6ab = 3(a+4b)/(6a)b = (a+4b)/2b = (a+4b)/2b
б) 15b-20c/10b = 5(3b-4c)/(10b) = 3b-4c/2b = (3b-4c)/(2b)
в) 2a-4/3(a-2) = 2(a-2)/3(a-2) = 2/3
г) 5x(y+2)/6y+12 = 5x(y+2)/6(y+2) = 5x/6

4)
а) y²-16/3y+12 = (y+4)(y-4)/(3)(y+4) = (y-4)/3
б) 5x-15y/x²-9y² = 5(x-3y)(x+3y)/(x-3y)(x+3y) = 5
в) (c+2)²/7c²+14c = (c+2)²/7c(c+2) = (c+2)/7c
г) 6cd-18c/(d-3)² = 6c(d-3)/(d-3)² = 6c/(d-3)
д) a²+10a+25/a²-25 = (a+5)²/(a+5)(a-5) = a+5/(a-5)
е) y²-9/y²-6y+9 = (y+3)(y-3)/(y-3)² = (y+3)/(y-3)