Question

Sam has $2,450 in his bank account. He spends $20 each week on gas money. After how many weeks will sams account balance fall below $1000 in inequality form?

Answer 1

• 2450 -20w < 1000
• 73 weeks

Explanation:

The balance (b) in Sam's account will be the initial balance less 20 times the number of weeks (w) that he withdraws gas money.

b = 2450 -20w

We want the inequality to express the condition that this balance is below 1000:

b < 1000

2450 -20w < 1000 . . . . . substitute for b

__

The solution to this can be found by subtracting 2450, then dividing by -20.

-20w < -1450

w > 72.5

If weeks are counted in whole numbers, Sam's balance will be below $1000 after 73 weeks.