Tom, Dorothy, and Sammy went on a vacation and agreed to split the costs evenly. During their trip Tom paid \$ 105, Dorothy paid \$ 125, and Sammy paid \$ 175. In order to share the costs equally, Tom gave Sammy t dollars, and Dorothy gave Sammy d dollars. What is t-d ?
Answer Choices
A. 15
B. 20
C. 25
D. 30
E. 35