If Robert buys a candy bar for 78 cents, how much change does he get back from a one-dollar bill?

Solution:

A mathematical statement is given in the question.

We should convert the given mathematical statement into an algebraic expression.

After this conversion, we can solve for x.

We know that 

One dollar = 100 cents

Shop keeper will keep 78 cents and return the change to him

78 + x = 100

So the change received by Robert x = 100 - 78 = 22 cents

Therefore, Robert gets back 22 cents.

If Robert buys a candy bar for 78 cents, how much change does he get back from a one-dollar bill?

Summary:

If Robert buys a candy bar for 78 cents, he gets back 22 cents from a one-dollar bill.