Alrighty,
With A, we have Mrs. Ardion boating at a steady 15 mph, so that means that if we have X hours, could be 5 could be 1, but you would take that original 15mph, and you would multiply it by the amount of hours she had traveled, for example if we have 3 hours then you would do 15x3 which would give you a sum of 45 miles.
B
If Mrs. Thomason started to kayak 1/4 of an hour before Mrs. Ardoin then we would take 1/4 of an hour, which is 15 minutes so lets say Mrs. Ardoin had been boating for 2 hours, then Mrs. Thomason had been boating for 2 hours and 15 minutes. minutes. Its what the amount of time Mrs. Ardoin had gone plus 15 minutes.
C
Mrs. Thomason is going at 10 miles an hour, and we already know that Mrs. Ardoin is going 15 miles an hour, so if we take T for Thomason, and A for Ardoin, we get 15 * X (amount of hours) = amount of miles traveled by Mrs. Ardoin, so for Mrs. Thomason its about the same, 10 * X (amount of hours) = amount travelled.
D
If Mrs. Thomason had left 15 minutes earlier, then if we do the math which would be 10 divided by 15 to get 0.6, which would mean that she is 0.6 miles ahead of Mrs. Ardoin, so if we do the math Mrs. Ardoin would meet up with Mrs. Thomason about 22 minutes into the race.
Hope this helped!