My question is about Math

Question

Troy and Lisa were shopping for school supplies. Each purchased different quantities of the same notebook and thumb drive. Troy bought 6 notebooks and 5 thumb drives for $122. Lisa bought 13 notebooks and 12 thumb drives for $283. Find the cost of each notebook and each thumb drive.

Answer 1

6N + 5T = 122

13N + 12T = 283

multiply 1st equation by 12 and 2nd by 5 to get

72N + 60T = 1464

65N + 60T = 1415 subtract to get

7N = 49

N = 49/7 = $7 per notebook

T = (122-42)/5 = 80/5= $16 for a thumb drive