y, если -y=20;-4,05;12 3/5;8 1/4

y=-20
y=4,05
y=-12,3/5
y=-8,1/4

-y = 20
-y = -1 * (-20)
-1 * (-y) = -1 * (-1) * (-20)
y = 1 * -20
y = -20

-y = -4,05
y = 4,05

-y = 12 [tex] \frac{3}{5} [/tex]
y = -12 [tex] \frac{3}{5} [/tex]

-y = 8 [tex] \frac{1}{4} [/tex]
y = -8 [tex] \frac{1}{4} [/tex]