Lila wants to rewrite 10/25 as a percent. She decided to represent 10/25 first in a picture. How many sets of 25 will she need to make 100? How many sets of shaded squares will she need? How many shaded squares is that in total?

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

on friday there were 15 birds

-2

7 - 9 = -2

reversed:

-2 + 9 = 7