7/10 of Delia's money is equal to 1/5 of

Sarah's money. They have $225 altogether
How much does Delia have?

Delia's money --- d

Sarah's money --- s

d+s = 225

(7/10)d = (1/5)s
7d/10 = s/5
35d = 10s
d = 10s/35

sub into d+s = 225
10s/35 + s = 225
times 35
10s + 35s = 7875
s = 175
then d = 225-175 = 50

Deliah has $50 and Sarah has $175

check: (7/1)(50) = 35
(1/5) of 175 = 35
yeahhh!