I think you need to add a picture?
Answer:
The blank is 3
Step-by-step explanation:
1 - Give the blank a variable
x = our blank
2 - Write it out

3 - Get the denominators equal

4 - Simplify

5 - Solve for the numerators
30+7x = 51
-30 -30
7x = 21
x = 3
(553-265)/48=6
6 hours spent repairing the car