If Ken gave Andrew 10 more marbles than Andrew already had. Andrew now has 100 marbles. How many marbles did Andrew have to start with?

The poorly Worded question leaves doubt as to what the answer is. If Ken gave Andrew 10 more marbles, and Andrew ends up with a hundred, Andrew started with 90. If Ken gave him the same number Andrew already had plus ten to equal 100 marbles, Andrew started with 45 and Ken gave him 55.