Question 1162403
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For Maria, 20th from the front of the line means #20 in the line.<br>
For her classmate, 23rd from the end of a line of 35 means there are 35-23 = 12 in front of her, which means she is #13 in the line.<br>
If the question is really how many classmates Maria has, the answer is 20-13 = 7.<br>
If the question is supposed to be how many students are in Maria's class, then the answer is (20-13)+1 = 8.<br>