Two sisters, Allie and Bonnie are saving money for a trip to Europe. Allie has $1500 and adds $500 each month to this amount. Bonnie has $2300 and adds $400 each month to this amount. How many months must Allie save to exceed the amount of money that Bonnie has saved?

Question

across · Answer

$$y=mx+b$$In this case, $m_A=500$, $m_B=400$, $b_A=1500$ and $b_B=2300$, where the subscripts stand for the first letter of each girl's name.

Plug some values in and you'll get a system of two equations and two unknowns; solve for $x$.

across · Answer

Where are you guys getting these numbers from?

anonymous · Answer

The answer is either 7 months , 8 month, 9 months, and 10 months? so which one? i'm having a hard time figuring this out

ragingsquirrel · Answer

7 is my best guess.

ragingsquirrel · Answer

Lemme go over it again.

across · Answer

$$y=500x+1500,$$$$y=400x+2300.$$
$$500x+1500=400x+2300,$$$$100x=800,$$$$x=8.$$

across · Answer

Just follow the procedure I outlined above...

anonymous · Answer

Thankyouu! i understand now!