1. First, you want to figure out how much one text message costs. To do this, divide the dollar amount (28.20) by the number of text messages (188). You get 0.15, or $0.15 per text message.
2. Using this $0.15 per text message, you can calculate how much 63 text messages costs. You simply multiply $0.15 by 63 to get $9.45, which is your answer.