



 
Hi Sara, let me illustrate with 5x + 15y = 70. The task is to manipulate the equation, always keeping the two sides equal, and end with an equation of the form
There are four operations I can perform and still maintain the equality of the two sides of the equation.
Looking at the equation I notice that each of the numbers is divisible by 5 so I can divide each side by 5 to obtain
I don't want the x on the left side of the equation so subtract x from each side.
Almost there. Finally divide each side by 3.
Now try your problem,  


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