In order to solve this problem, we have to set up a proportion. But first, we must add $1.40+$1.60 to find out the denominator for our proportion. The answer to that addition problem is $3.00. We are now ready to set up the proportion. $1.60/$3.00 =x/$180.00. So we cross multiply (1.6*180=288) then divide our answer (288/3) which gives us a final answer of 96. Therefore, Rosa's mother added a total of $96.00