1)

6х²у = 1,5 * 4х²у =

= 1,5 * 3 = 4,5,

2)

4х⁴у² = х²у * 4х²у = 1/4*4х²у * 4х²у = 1/4 * (4х²у) =

= 1/4 * 3² = 1/4 * 9 = 9/4 = 2 1/4   (или  2,25),

3)

-3х⁶у³ = -3 * (4х²у)³ / 4³ = -3 * (4х²у)³ * 1/64 = -3/64 * (4х²у)³ =

= -3/64 *  3³ = -3/64 * 27 = -81/64 = -1 17/64