When you use place value to exchange equal amounts when renaming a number , what are you doing

Three people are traveling and need to exchange the currency of their native country for the currency of the country they are visiting. drag each exchange to the category that shows the ratio of currencies in that exchange.

Collin did the work to see if 10 is a solution to the equation r/4=2.4

Astudent was asked to find the square of 7x+3. the student quickly wrote (7x+3)^3= 49x^2+9. identify the student's error and provide the correct answer.