Use the fact that
5.7 X 4.3 = 24.51
to work out
57 X 4.3

57 x 457 x 4.3 = 10 x (5.7 x 4.3) = 10 x 24.51 = 245.1

Step-by-step explanation:

If we look closely at the two equations you will see the following...

57 x 4.3 = 10 x (5.7 x 4.3)

(Since we know what 5.7 x 4.3 equals to we just substitute the value of 24.51 and get...)

57 x 4.3 = 10 x 24.51

57 x 4.3 = 245.1