Creatively image a question and justification for this answer: 10
The question is: Miss Grayson's class raised $50 for their field trip. Aside from that, each of her students contributed $5 each. There are 20 students in her class, and the cost of the trip is $7 for each student. After all the field trip costs were paid, how much is left in Miss Grayson's class fund?
Step-by-step reasoning process: The contribution of the students amounted to $5 x 20 = $100. So Miss Grayson's class had $100 + $50 = $150 in all. The cost of the field trip amounted to $7 x 20 = $140. Therefore, the class of Miss Grayson is left with $150 - $140 = $10.