6(1 + 3R) = 2(10R - 9) -4R

R=-12

Step-by-step explanation:

6(1 + 3R) = 2(10R - 9) -4R

Distribute 6 through the parentheses

6+18R=2(10R-9)-4R

Distribute 2 through the parentheses

6+18R=20R-18-4R

Collect like terms

6+18R=16R-18

Move the variable to the left-hand side and change its sign

6+18R-16R=-18

Move the constant to the right-hand side and change its sign

18R-16R=-18-6

Collect like terms

2R=-18-6

Calculate the difference

2R=-24

Divide both sides of the equation by 2

R=-12

if you'd make me brainliest that'd be great, if not its ok as well! I hope this helped!!!

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.