Question

For how many days is the total cost $300? ___days

Initial Value 8
Rate of Change 15

Answer 1

• b=initial value=8
• m=rate if change(Slope)=15

Equate

`\\ \sf\longmapsto y=mx+b`

`\\ \sf\longmapsto 300=15x+8`

`\\ \sf\longmapsto 300-8=15x`

`\\ \sf\longmapsto 292=15x`

`\\ \sf\longmapsto x=(292)/(15)`

`\\ \sf\longmapsto x=19.5`

Answer 2

• ≈ 19.5 days

Explanation:

• Initial Value b = 8
• Rate of Change m = 15

Equation of the line:

• y = 15x + 8

Find x when y = 300:

• 15x + 8 = 300
• 15x = 300 - 8
• 15x = 292
• x = 292/15
• x ≈ 19.5 days