You cant solve these if they are not equating up to something hence incomplete question.
I might be wrong but don’t you need two equations to do the elimination process?
80% like crisps
75% of the 80% like chocolate.
What percent of the total are the children who like chocolate and crisps?
75% of 80% = 60%
This 60% of children like chocolate and crisps
If its 20 more than last month that means x + $20 = $70, solve that and you get x = $50, last month she saved $50
