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Writing a Linear Function from a Word Problem · Easy Worksheet 1

Writing a Linear Function from a Word Problem — Easy Worksheet 1

Grade 8 · Whoobee    Name: ____________________   Date: __________

Write an equation in the form y = mx + b for each situation.

How to solve

The initial value b is the starting amount or fixed fee, the value of y when x = 0. The rate of change m is how much y changes for each 1 unit of x; it is negative when the amount goes down. When you are given two data points instead, m = (change in y) ÷ (change in x), and you find b by working back to x = 0. Then write y = mx + b.

Example

A sunflower is 22 cm tall and grows 3 cm every week. Write an equation for y, the height of the sunflower in cm, after x weeks.

Answer: y = 3x + 22

right so far
1 A pool holds 150 liters of water, and a hose adds 37 liters every minute. Write an equation for y, the water in the pool in liters, after x minutes.
2 A gym charges a $58 sign-up fee plus $40 per month. Write an equation for y, the total cost in dollars, after x months.
3 A plumber charges $69 for a visit plus $45 per hour. Write an equation for y, the charge in dollars, after x hours.
4 A taxi ride costs $4 plus $2 per mile. Write an equation for y, the fare in dollars, after x miles.
5 Sam has $131 saved and adds $14 every week. Write an equation for y, the amount saved in dollars, after x weeks.
6 A pool holds 168 liters of water, and a hose adds 17 liters every minute. Write an equation for y, the water in the pool in liters, after x minutes.
7 A taxi ride costs $4 plus $5 per mile. Write an equation for y, the fare in dollars, after x miles.
8 A sunflower is 23 cm tall and grows 4 cm every week. Write an equation for y, the height of the sunflower in cm, after x weeks.

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