Megan has $45 on a coffee gift card. she buys a mug for $9 and plans to spend the rest on $4 cups of coffee. how many cups of coffee can she buy?

Cherie works in retail and her weekly salary includes commission for the amount she sells. the equation s=400+0.15c models the relation between her weekly salary, s, in dollars and the amount of her sales, c, in dollars. interpret the slope of the equation.