Question

Jonah's bank account has a balance of $150. He withdraws $20 from his bank account

each day for four days. What will Jonah's account balance be four days from now?

Answer 1

Answer: $70

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Step-by-step explanation:

• x = number of days that elapsed
• y = bank balance in dollars

His bank balance is represented by the linear equation y = -20x+150.

The slope -20 means the balance goes down by 20 dollars each day. The y intercept 150 is the starting balance.

Plug in x = 4 to find the balance after four days

y = -20x+150

y = -20*4+150

y = -80+150

y = 70

His balance is $70 after four days. The -80 in the third step indicates the balance had gone down by $80.

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Another way to see why the answer is $70 is to write it out like this

day 0 = $150

day 1 = 150-20 = $130

day 2 = 130-20 = $110

day 3 = 110-20 = $90

day 4 = 90-20 = $70