Hi, can you please help me with this word problem? Thank you so much!

Question

Hi, can you please help me with this word problem? Thank you so much!

Marco owed his father $150 and began paying him back $20 at the end of each week, beginning November 1. Joni owed her father $130 and began paying him back $15 at the end of each week, beginning on the same day. What Marco owed his father in dollars at the end of n weeks can be represented by f(n) = 150 – 20n. What Joni owed her father in dollars at the end of n weeks can be represented by g(n) = 130 – 15n.

After how many weeks, Jonie and Marco each owed their fathers the same amount.

Answer 1

When

f(n) = g(n)

150 - 20n = 130 - 15n

 

Can you solve for n?

Answer 2

Hy Brenda ,

 

The important clue here is when they say both The girls owe the same amount so what they mean is equate both the functions 

 

so we get

 

150 - 20n = 130 - 15n

 

 

Now n gives us the number of weeks so solve for n

 

20n - 15n = 150 - 130

 

5n = 20

 

n = 4

 

Now check your solution 

 

150-20(4) = 70

 

130 - 15(4) = 70

 

So our answer checks out after 4 weeks both girls who their dads the same amount of money .

 

regards,

 

mayuran