Jacob’s weekly take-home pay is n dollars. Each week he uses

We see that 1 - (4n/5) = n/5 is saved each week. Let’s let w = the number of weeks it will take to save 500 dollars and create the equation:

n/5 x w = 500

nw = 2500

w = 2500/n weeks.

Answer: B

Take Home weekly pay = n

Weekly Saving = n - (4/5)n = n/5

Weeks to be spent to save $500 = 500/(n/5) = 2500/n

Answer: Option B

In this question,i used this approach

Took salary earned by Jacob per week as 50 dollars

In this his expenses were 40 dollars and he saved 10 dollars

It is given that he saved 500 dollars after some weeks.

If you can notice as you increase the number of weeks, an AP is formed in the amount which he is saving per week,To Explain this

1st week $50 Expenses $40 Saved $10
2st week $100 Expenses $80 Saved $20
3st week $150 Expenses $120 Saved $30

so in the he saved 500 dollars, calculated by, last term = a + (n-1) d
where a =10, d =10 and last term = 500

Now you have to find out of the answer options which option will give you 50 as the answer

Making the answer as

I feel Once you realize its an AP this is an easy approach.