[tex]\qquad\qquad\huge\underline{{\sf Answer}}♨[/tex]
Let's solve ~
[tex]\qquad \sf \dashrightarrow \:40 + x + 25 = 180[/tex]
[tex]\qquad \sf \dashrightarrow \:x + 65 = 180[/tex]
[tex]\qquad \sf \dashrightarrow \:x = 180 - 65[/tex]
[tex]\qquad \sf \dashrightarrow \:x = 115[/tex]
I hope you understood the procedure, please let me know if you have any doubts