Help asap ! Kathy and Gaby are enrolled in a University program to study abroad in England and then in South Africa. They realize that they will have to convert US dollars (USD) to Euros (EUR) in England, and then convert EUR into South African Rand (ZAR) for their time in South Africa.

They, thinking critically, understand that there must be a mathematical formula that allow them to make conversions directly, from USD to EUR, and then to ZAR.

What must they do, mathematically speaking, to know how many Rands (ZAR) they would have based on the number of dollars (USD) that they have now?
Once they return to their home country, they will need to reconvert all their Rands (ZAR) to Euros (EUR), and then the EUR to dollars (USD).

What do they need to do, mathematically speaking, to calculate how many USD will they have at the end of their trip abroad?