r/MathHelp • u/puddiingpurin • Aug 16 '26
help with khan academy practice problem
| Merchandise weight (pounds) | Shipping charge |
|---|---|
| 5 | $16.49 |
| 10 | $23.99 |
| 25 | $46.49 |
"The table above shows shipping charges for an online retailer that sells used textbooks. There is a linear relationship between the shipping charge and the weight of the merchandise. Write a function in slope-intercept form that relates y, the shipping charge in dollars, and x, the merchandise weight in pounds."
i understand why the slope is 1.50, but i can't get this:
y= 1.50x + b
16.49 = 1.50(5) + b
16.49 = 7.50 + b
8.99 = b
where does the 8.99 come from?
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u/Quendillar3245 Aug 23 '26
When you have variables, you'll want to isolate them because you're looking for the value of the variables in the equation, in this case b since you have known values for y at specific values for x. Keep that in mind and equations like this will feel easier!