Let the number of yards she trimmed be t
She trimmed 5 more yards than she cut and she mad $415, so
20t+15(t-5)=415
We first distribute the second number so this equals
20t+15t-75=415
Then we add 75 to both sides, getting
20t+15t=490
This means that
35t=490
And we divide both sides by 35 to get
t=14
So, she trimmed 14 yards