Ella started with a certain amount of money. She spent 2/5 of her money. She
earned Php5.00 the next day. Later she lost 3/7 of her money, but she still has
Php20.00 left. How much did she have at first?
Solve it backwards.
Begin with the Php20.00 she had left.
Going back a step,
Later she lost 3/7 of her money,...
So Php20.00 was 4/7 of what she had before she lost 3/7 of her money, so we
divide Php20.00 by 4/7. 
So she had Php35.00 before she lost 3/7 of it.
Going back another step:
She earned Php5.00 the next day.
So before she earned Php5.00, she only had Php30.00
Going back another step:
She spent 2/5 of her money.
So the Php30.00 was only 3/5 of the money she had before she spent 2/5 of it.
so we divide Php30.00 by 3/5. 
So she started with Php50.00.
Edwin
