owes $29.50 in april
plan: $15 for 350 messages + $0.25 for each additional message
steps:
15 + 0.25x = 29.50 (let x = number of additional messages)
0.25x = 14.50 (subtract by 15 on both sides)
x = 58 (divide by 0.25)
58 + 350 = 408 messages
9.5m questions
12.2m answers