This is a distributive problem, so 3/5 x r will give you 3/5r and 3/5 x -7 will equal -4.2
Your equation will look like 3/5r - 4.2=1
Now you have to solve this...
So you add 4.2 to both sides to get your equation to like like this,
3/5r -4.2=1
+4.2 =4.2 ----> 3/5r=5.2 now divide 5.2 by 3/5 to make r = 8.666