Algebra Play

A number trick: think of a number, add 5, double it, subtract 10, then halve it — you get back the original number. Disha tries it with 7 and it works. She says the trick only works for 7, not for every number. Is Disha right?

The equation is 3x = 15. Ishaan writes x = 15 + 3 = 18. His friend says this method is wrong. Who is right?

Asked to simplify 4x + 2x, Rohit says the answer must be a single number, so the question is incomplete. Meera says the answer is 6x. Who is right?

Mehar tries x=2: 2+2=4 and 2²=4, both come out equal. She says this proves x+x always equals x² for every x. Is Mehar right?

Asked to simplify 3x + 2y, Karan writes 5xy. Nita says 3x + 2y cannot be combined into one term at all. Who is right?

Kabir solves x + 2 = 7 in one problem and gets x = 5. Later, in a different problem, he sees x + 3 = 10 and assumes x is still 5, without solving again. Is Kabir right?