You have already saved $55. You earn $9 per hour at your job. You are saving for a bicycle that costs $199. How do you write an inequality that represents the possible numbers of hours you need to work to buy the bicycle?

1 Answer
Aug 6, 2017

$55 + $9 x ge $199

You must work for at least 16 hours to be able to buy the bicycle.

Explanation:

Let x represent the number of hours you need to work to buy the bicycle.

You already have $55.

Rightarrow $55 + underline(" " " ") ge underline(" " " ")

You also earn $9 per hour.

Algebraically, this can be written as 9 x.

Rightarrow $55 + $9 x ge underline(" " " ")

You need to earn at least $199 to buy the bicycle.

Rightarrow $55 + $9 x ge $199

The ge sign is used because the left-hand side of the inequality must be "greater than or equal to" $199.

Let's find out how many hours you need to work to buy the bicycle.

Subtracting $55 from both sides of the inequality:

Rightarrow $55 - $55 + 9 x ge $199 - $55

Rightarrow $9 x ge $144

Dividing both sides by $9:

Rightarrow frac($9 x)($9$) = frac($144)($9)

therefore x ge 16

Therefore, you need to work at least 16 hours to afford the bicycle.