I need some help with my homework so may someone help me not in a rush just need this done

Answer:
-25
Step-by-step explanation:
First he bought 3 tires which total costed 105, then returned 2, so he got $70 back, meaning he had $35. Then he found 2 $20 bills, which raised his total to $75. Then, he bought a phone for $90, so he has -25 dollars left