Copyright © University of Cambridge. All rights reserved.
'Symbol' printed from https://nrich.maths.org/
Show menu
Answer
: $7$
$3\oplus 5 = 3\times 5 + 3 +5 = 23$ and $2\oplus x = 2x + 2+ x= 3x + 2$.
These are equal, so $3x + 2 = 23$, i.e. $x=7$.
This problem is taken from the
UKMT Mathematical Challenges
.
You can find more short problems, arranged by curriculum topic, in our
short problems collection
.