4 1/4 - 6 2/3 : 2 1/2 = -24 : 6 - (-2) x 5= (-4)² x 5²

1). 4¼ - 6⅔ : 2½
= 17/4 - 20/3 : 5/2
=17/4 - 40/15
=17/4 - 8/3
=51/12 - 32/12
=19/12
=1 9/12
=1¾
2).-24 : 6 - (-2)×5
= -4 - (-2) ×5
=-4 -(-10)
= -4 +10
=6
3).(-4)² × 5²
=1/16 ×25
=25/16
=1 9/16