Here we go:
9=3x3 10=5x2
Then we take the 3 from the 9, and the 5 from the 10, 3x5=15
Then we take the 3 from the 9 and the 5 from the 10, 3x2=6
Then we add the products: 6+15=21!!!
Thanks for the negative points...
:(
I meant you gave it all to got to find a valid solution for 9+10=21
You gave it all you got!!!
What? 😕