1.5×[

19

21

÷6

1

3

×（0.7-0.66）]×4.9，
=1.5×[

19

21

÷

19

3

÷0.04×4.9，
=1.5×[

19

21

×

3

19

×25]×4.9，
=1.5×

25

7

×4.9，
=26.25．