2.48

5.75

58.6

( 1)6.5×6.5+6.5×3.5

=6.5×(6.5+3.5)

=6.5× 10

=65

(2)2.5×(2.4+0.8)× 1.25

=2.5×3.2× 1.25

=(2.5×4)×(0.8× 1.25)

= 10× 1

= 10

( 1) 1.8+( 1.8×2-0.6)

= 1.8+(3.6-0.6)

= 1.8×3

=5.4

(2)3.75÷0.25- 1.8×4.5

= 15-8. 1

=6.9

(3)(4.4×2.5+ 19)÷3

=( 1 1+ 19)÷3

=30÷3

= 10