Roxanne has $20 and she wants to buy some shirts. she picks one shirt that costs $10.99 and two shirts that cost $4.99 each.

which statement best describes if an exact total or an approximate total should be calculated?

a.
roxanne must add the exact cost of the three shirts so she will know if she has enough money to buy the third shirt.

b.
roxanne can round the prices of the shirts to the nearest dollar and then add to estimate if she has enough money.