private String getPrecedence(String op1, String op2){
		
		String multiplicativeOps = "*/%";
		String additiveOps = "+-";
		
		if ((multiplicativeOps.indexOf(op1) != -1) && (additiveOps.indexOf(op2) != -1))
			return op1;
		else if ((multiplicativeOps.indexOf(op2) != -1) && (additiveOps.indexOf(op1) != -1))
			return op2;
		else if((multiplicativeOps.indexOf(op1) != -1) && (multiplicativeOps.indexOf(op2) != -1))
			return op1;
		else 
			return op1;
	}