Question 870652
r = Rods's share
p = Paul's share
j = Jack's share
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Write an equation for each statement. We want to get p and j in terms of r
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The 3 boys found 20.30 dollars in their brother's old money box, 
r + p + j = 20.30
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Ron was to get one and a third times as much as Paul,
r = 1{{{1/3}}}p
r = {{{4/3}}}p
Mult by 3
3r = 4p
p = {{{3/4}}}r
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 but one and a half times as much as Jack.
r = 1{{{1/2}}}j
r = {{{3/2}}}j
mult  by 2
2r = 3j
j = {{{2/3}}}r
:
r + p + j = 20.30
replace p and j
r + {{{3/4}}}r + {{{2/3}}}r = 20.30
mult by 12, cancel the denominators
12r + 3(3r) + 4(2r) = 12(20.30)
12r + 9r + 8r = 243.6
29r = 243.6
r = {{{243.6/29}}}
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You can confirm this for yourself, find p and j see if they add up to 20.30