Question 1113692
.
<pre>
 R +     J = 120        (1)    (R pounds of Rio and J pounds of Java)
5R + 7.50J = 7*120      (2)    ("money" equation)


Multiply eq(1) by 5 (both sides). Keep eq(2) as is:

5R +    5J = 5*120      (1')
5R + 7.50J = 7*120      (2')


Subtract eq(1') from eq(2'). In this way, you eliminate R and get a single equation for the unknown J:

7.50J - 5J = 7*120 - 5*120

2.5J = 240  ====>  J = {{{240/2.5}}} = 96.


<U>Answer</U>.  96 pounds of Java coffee and the rest  120-96 = 24 pounds of Rio coffee.
</pre>

Solved.


On the way, you learned how the Elimination method works.


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in this site.


Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this online textbook under the topic "<U>Systems of two linear equations in two unknowns</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.