Lucy's savings account has 35% more money than her sister edy's. together, the girls have saved a total of $206.80. how much money has each girl saved?

X=Lucy´s money
y=Edy´s money
we can suggest this system of equations:
x=y+(35/100)y    ⇒x=135y/100
x+y=206.8

solve by substitution method. 
(135y/100)+y=206.8
Least common multiple=100
135y+100y=20680
235y=20680
y=20680/235=88

then:
x=135y/100=135(88)/100=118.8

Lucy´s money=$118.8
Edy´s money=$88

To check:
Together, the girls have   saved a total of $118.8+$88=$206.8
Lucy´s savings account has: $88+(35/100)$88=$118.8, 35% more monty than Edy´s. account.     .                                                                                                                            

The first digit is in the middle school 100s place