18 is 36% of what number?

The number is 50

Step-by-step explanation:

Step 1:  Make an equation

x * 0.36 = 18

0.36x = 18

Step 1:  Divide both sides by 0.36

0.36x / 0.36 = 18 / 0.36

x = 50

 The number is 50

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.

d

step-by-step explanation:

d