Which describes a situation when an estimation is appropriate? a. margo wants to buy a sweater for $15.98 and a pair of socks for $1.98. she has $20. she wants to know if she has enough money to buy both. b. margo buys a sweater for $15.98 and a pair of socks for $1.98. she gives the cashier $20. the cashier wants to know how much change to give margo.