In angle JKL angle K is 9 more than angle J and angle L is 21 less than twice angle J

Answer 1

I think you must mean triangle JKL?

Let x = angle J

x+9 = angle K

2x-21 = angle L

The sum of these must be 180, so you can set up the following equation

x+x+9+2x-21 = 180 Combine like terms

4x-12 = 180 Add 12 to both sides

4x=192 Divide both sides by 4

x=48

Now we can solve for all the other angles

Let x = angle J = 48

x+9 = angle K = 48+9 = 57 = angle K

2x-21 = angle L = 2(48)-21 = 75 = angle K