Write the equation of a linear model
Write the equation (y = mx + b) of a linear relation from a described fixed value and rate of change. Unlimited questions, five difficulty levels, and a full worked solution every time — free.
Try one
A gift card starts with $20.00 and loses $2.00 for every song downloaded. Write an equation for the balance B in terms of n, the number of downloads.
- B = −2n - 20
- B = 2n + 20
- B = 20n - 2
- B = −2n + 20
Answer: B = -2n + 20
See one solved, step by step
A gift card starts with $20.00 and loses $1.00 for every song downloaded. Write an equation for the balance B in terms of n, the number of downloads.
- B = n + 20
- B = 20n - 1
- B = −n - 20
- B = −n + 20
📘 Worked solution
1A gift card starts with $20.00 and loses $1.00 for every song downloaded.This describes a starting amount (the B-intercept) plus a rate that changes with downloads (the slope).
2slope (rate) = −1It decreases by 1 for every download, so the slope is negative: -1.
3B-intercept (starting value) = 20That's the amount before any downloads happen — where n = 0.
4B = −n + 20Put the slope and starting value together in the form B = mn + b.
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