Where are the variables for the equation?
During week 2, he could type 15 words per minute, at his fourth week, he could type 30. So 30-15=15. He could type 15 words faster on week 4 than he could at week 2.
8 is a whole number, so this will be the whole number part of our mixed number.
0.25 is a decimal, where 25 is in the HUNDREDths place, so we write 25 as a fraction over 100.

Simplify by dividing 25 to the numerator and denominator.


So our fraction is

0.55 is a decimal, where 55 is in the HUNDREDths place, so we write 55 as a fraction over 100.

Simplify by dividing 5 to the numerator and denominator.


So our fraction is


To convert this to a decimal, just divide 5 / 8