SOLUTION: susan is 4/5 as old as Ronald. four years ago, she was 3/4 as old as ronald. how old each?

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Question 1021544: susan is 4/5 as old as Ronald. four years ago, she was 3/4 as old as ronald. how old each?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +s+=+%284%2F5%29%2Ar+
(2) +s+-+4+=+%283%2F4%29%2A%28+r+-+4+%29+
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Substitute (1) into (2)
(2) +%284%2F5%29%2Ar+-+4+=+%283%2F4%29%2A%28+r+-+4+%29+
Multiply both sides by +20+
(2) +16r+-+80+=+15%2A%28+r+-+4+%29+
(2) +16r+-+80+=+15r+-+60+
(2) +r+=+20+
and
(1) +s+=+%284%2F5%29%2Ar+
(1) +s+=+%284%2F5%29%2A20+
(1) +s+=+16+
Susan is 16 and Ronald is 20
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check:
(2) +s+-+4+=+%283%2F4%29%2A%28+r+-+4+%29+
(2) 16+-+4+=+%283%2F4%29%2A%28+20+-+4+%29+
(2) +12+=+%283%2F4%29%2A16+
(2) +48+=+48+
OK