Question

Michael and Lindsey are saving money. Michael begins with $20 and saves $5 per week. Lindsey begins with no money, but saves $10 per week. Enter the number of weeks it will take for Lindsey and Michael to save the same amount of money.

Answer 1

Let
x----------> number of weeks
y----------> saved money

we now that

Michael begins with $20 and saves $5 per week
so
y=20+5x------> equation 1

and
Lindsey begins with no money, but saves $10 per week
y=10x-------> equation 2

the number of weeks it will take for Lindsey and Michael to save the same amount of money is when equation 1 is equals to equation 2

therefore
20+5x=10x------> 10x-5x=20------> 5x=20-----> x=20/5-----> x=4 weeks

the answer is 
4 weeks