Adam wants to mix 10 cups of fertilizer from concentrate. he needs to mix one part of fertilizer concentrate with 4 parts of water. he wrote the system of equations to represent the amount fertilizer concentrate and water needed and then graphed the first line.

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.

at least two

step-by-step explanation: