3. At the mall, Leona bought a T-shirt and a book for a total of $23. The book costs $12. How much did the T-shirt cost? (a) What is the unknown information?
(b) Let x represent the unknown information. Write an addition equation that models the problem
(c) Solve the equation.
(d) Answer the question.

Without any equipment, you can see stars that are 2{,}800{,}0002,800,0002, comma, 800, comma, 000 light-years away. by looking through a small telescope, you can see stars that are 3{,}112{,}000{,}0003,112,000,0003, comma, 112, comma, 000, comma, 000 light-years away. approximately how many times as far can you see using a small telescope as without any equipment?