Answer:
15
Step-by-step explanation:
Let us first write an equation where the unknown number is represented with variable x. <em>The sum of a fifth of x and two is five:</em>

Great! Let's solve for x by isolating the variable.

<u>Therefore, the unknown number is 15.</u>
<u />
<em>I hope this helps! Let me know if you have any questions :)</em>
A(10) = <span>9(10) + 9= 90+9 =99
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Amanda Billy
1st week 10 5
2nd week 20 10
3rd week 30 20
4th week 40 40
<span>
A) Amanda's method is linear because the number of minutes increased by an equal number every week.</span>
common difference is 10.
1st week 0 + 10 = 10
2nd week 10 + 10 = 20
3rd week 20 + 10 = 30
4th week 30 + 10 = 40
Billy's method is exponential:
5(2)^x
1st week 5(2⁰) = 5(1) = 5
2nd week 5(2¹) = 5(2) = 10
3rd week 5(2²) = 5(4) = 20
4th week 5(2³) = 5(8) = 40