Question 288423
Mariana's savings can be represented by {{{MarianaSaving = 50 + 3w}}}
Luis's savings can be represetned by {{{LuisSavings = 5.5w}}}
You are asked to find when Luis has more saved that Mariana

{{{LuisSavings > MarianaSavings}}}
{{{5.5w > 50 + 3w}}}
{{{2.5w > 50}}}
{{{w > 50/2.5}}}
{{{w > 20}}}

So at 20 weeks they have the same amount. After 20 weeks, Luis has more.
Note this assumes neither get any interest on their accounts.