If I give piano lessons to 10 students per week for a half hour lesson and five students per week for a full hour lesson the $10 per half hour less than 16 per lesson how many dollars will she earn per week what expression is used

Let the number of half hour lessons be x and the number of full hour lessons be y.

Given that the piano teacher charges $10 per half hour lesson, the total earned from the half hour lessons would be 10x dollars.
Also, given that the piano teacher charges $16 per full hour lesson, the total earned from the full hour lessons would be 16y dollars.
The expression that represents the total amount earned per week would be 10x + 16y dollars.