standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
problem_activity: Naja brought $20 to the corner store.
She spent $3.49 on candy.
She spent $5.79 on a Jamaican beef patty.
How much money did Naja have left?


aligns: no