SOLUTION: A plum and a pineapple cost the same as three peaches. Two plums cost the same as a peach. How many plums cost the same as a pineapple?

Question 159655: A plum and a pineapple cost the same as three peaches. Two plums cost the same as a peach. How many plums cost the same as a pineapple?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A plum and a pineapple cost the same as three peaches.
pl + pi = 3pe
or
pl = 3pe - pi
:
Two plums cost the same as a peach.
2pl = pe

How many plums cost the same as a pineapple?
;
pl = 3pe - pi: from the 1st equation
:
Substitute 2pl for pe, from the 2nd equation
pl = 3(2pl) - pi
:
pl = 6pl - pi
:
pl - 6pl = -pi
:
-5pl = -pi
:
5pl = pi (5 plums = 1 pineapple}

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