PLEASE I’ve been stuck on these for 30 minutes now I have 0 clue what to do (Click on image)

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap

Isaac wants the equation below to have no solution when the missing number is placed in the box. which number should he place in the box?