Find the distance she ran during her first week of training
First, let that distance of the first week be x
We know that in the second week she ran 13 km MORE than the first which means the distance she ran in the second week is (13+x) km
And the total distance of first and second week is 145 km
=> x + (13+x) = 145
2x+13 = 145
=> x = (145-13)/2 = 66 km
So, she ran 66 km during her first week of training.