function run(string){
let a;
let b;
let i = string;
let x;
for ( a = 1 ; a <= 10; a++){
for(b = 1; b<=10; b++){
x = a+"+"+b;
if ( x == string){
return(string);
}
}
}
}
console.log(run(10+5));
console.log(run(55 - 7));
console.log(run(5 * 7));
console.log(run(5 / 7));