Let [tex]a=[/tex]the number of white marbles in Jar 1
Let [tex]b=[/tex]the number of white marbles in Jar 2
Total number of white marbles is [tex]a+b=90[/tex]
Jar 1 has [tex]a[/tex] white marbles and [tex]7a[/tex] red marbles so [tex]8a[/tex] marbles total
Jar 2 has [tex]b[/tex] white marbles and [tex]9b[/tex] red marbles so [tex]10b[/tex] marbles total
Since both jars have equal amounts of marbles, [tex]8a=10b[/tex]
We have a system of equations:
[tex]a+b=90[/tex]
[tex]8a=10b[/tex]
The number of red marbles in Jar 2 is [tex]9b[/tex] so we solve for [tex]b[/tex]
[tex]8a=10b[/tex]
⇒[tex]a=\frac{5}{4}b[/tex]
⇒[tex]\frac{5}{4}b+b=90[/tex]
⇒[tex]\frac{9}{4}b=90[/tex]
⇒[tex]b=40[/tex]
Number of red marbles in Jar 2 is [tex]9b=360[/tex]
So there are 360 red marbles in Jar 2.
