A. When Katina has $280 in her bank account, 4 months have passed. Plug 4 months into Malorie's bank account equation:
a = 50(4) + 100
a = 200 + 100
a = $300
B. Malorie's bank account changes at a greater rate. Katina's bank account amount increases by $20 each month, whereas Malorie's bank account increases by $50.
