Answer :
[tex]3.5r=3(4+0.5r)\\\\3.5r=3\times4+3\times0.5r\\\\3.5r=12+1.5r\ \ \ \ \ |substract\ 1.5r\ from\ both\ sides\\\\2r=12\ \ \ \ \ \ |divide\ both\ sides\ by\ 2\\\\r=6[/tex]
The 'answer' is the number that 'r' must be in order to make the equation a true statement. There's only one number that can do it. Here's how to find it:
Copy the equation: 3.5r = 3(4 + .5r)
Expand the right side: 3.5r = 12 + 1.5r
Subtract 1.5r from each side: 2r = 12
Divide each side by 2 : r = 6
Copy the equation: 3.5r = 3(4 + .5r)
Expand the right side: 3.5r = 12 + 1.5r
Subtract 1.5r from each side: 2r = 12
Divide each side by 2 : r = 6
