其它
An operator $$\star$$ acts on two numbers to give the following outcomes:  $$3\star2=51$$  $$5\star3=82$$  $$6\star1=75$$  $$9\star4=135$$  What is $$7\star5$$ equal to? 
Overseas Competition->Knowledge Point->Calculation Modules->Operations with New Definition
$$a\star b=\underbrace{(a+b)}\_{\rm{tens}} \underbrace{(a-b)}\_{\rm{ones}}$$ 