Answer:
5º
Explanation:
honestly im not sure if this will be right but i will try
since the triangles are i think the word is congruent, they equal the same
so 14x + 7 = 12x + 17
subtract 7 from both sides of the equal sign
and the equation is now 14x = 12x + 10
then subtract 12x from both sides of the equal sign
and now the equation is 2x = 10
divide both sides by 2
and x = 5