Miguel wants to buy a new stereo that costs $320. He has $40 in March, $80 in April, and $120 in May. If this pattern continues, in what month will he be able to buy the stereo?

Answer 1

Starting from February, after m months, he has 40m dollars. So, when does

40m = 320?
m=8
So, what's 8 months after February?