Question

At the beginning of the year, John had $40 in savings and saved an additional $13 each week thereafter. Isaac started the year with $80 and saved $9 every week. Let 'J' represent the amount of money John has saved tt weeks after the beginning of the year and let 'I' represent the amount of money Isaac has saved tt weeks after the beginning of the year. Write an equation for each situation, in terms of t, and determine the number of weeks after the beginning of the year until John and Isaac have the same amount of money saved.

Answer 1

10 weeks

Explanation:

Let’s replace ‘t’ with numbers going up starting from 0 on both sides of the equation. Repeat until you get to 10 and you see that both are equal at $170 has been saved after 10 weeks.

John’s equation: 40 (y intercept) + 13t (saved per week)

Issac’s: 80 (y intercept) + 9t (amount saved per week)

The y-intercept represents the amount of money already saved up.