Jose received a $100 gift card to his favorite coffee shop for his birthday. Every week he goes to the coffee shop and spends $5 on a drink.

a. Write an equation to represent the relationship between the amount of m money remaining on Jose’s gift card and the number of w weeks.

b. How many weeks will it be when Jose has only $15 remaining on his gift card?

Please help! I'll mark brainliest if correct :D