Tyler converted 0.0000783 to scientific notation. 0.0000783 = 78.3 x 10-6 analyze tyler’s work. is he correct? if not, what was his mistake?

No, he is not. The decimal has to be between 1 and 10, so the decimal would actually be between the 8 and 7 to make 7.83. Then, you multiply that decimal by a power of ten. Since the decimal was moved 5 spaces to the right, the power of 10 will be -5. So it would look like this: 
 7.83 x 10*-5. (the star means that the following number is a power of ten and meant to be small.)

That’s what i got when i looked up what the solutions were