It cost Santiago $6.00 to send 120 text messages. How much would it cost to send 133 text messages?
$6.00 / 120 = x / 133
Cross multiply.
$798 = 120 x
120 x = $798
x = $798 / 120 = $6 ∙ 133 / 6 ∙ 20 = $133 / 20 =$6.65
OR
$6.00 / 120 text messages = 6 ∙ $1 / 6 ∙ 20 =
$1 / 20 = $0.05 per text message
$0.05 ∙ 133 = $6.65