Answer:
He can grade 1.25 assignments in 1 minute.
Step-by-step explanation:
Because the teacher can grade 25 assignments in 20 minutes, we can dive 25 by 20 to get the constant rate.

So he can grade 1.25 assignments in 1 minute.
A triangle is 180 degrees. Depending on their angles: Right Angle - 90 degrees
Acute Angle - less than 90 degrees and Obtuse Angle greater than 90 degrees and under 180 degrees. Hope that helps.
Simplest way to do this:
number of books= 120
percentage represented by 120= 100%
increase current percent by 55%= 155%
: . 55% increase = original number of books * (155%)
= 120 * (155/100)
= 186