To evaluate 6 x 49, we write 49 as 50 - 1 and substitute:
6 x 49 = 6 x (50 - 1)
Now we operate multiplying by 6 both terms in the parentheses like follows:
6 x 49 = 6 x 50 - 6 x 1
Multiply:
6 x 49 = 300 - 6
And subtract:
6 x 49 = 294
This procedure corresponds to choice D
