Anything in front of a parenthesis is telling you to multiply it by what is inside of the paranthesis. So 5 should be multiplied by (r+9).
BUT whenever there is a plus or minus sign it's like those #s are in there own group or club and must each get multipled by the number in front. So 5 should be multiplied by r and by 9. It would look like this:
(5×r + 5×9) - (2×1 - 2×r)=1
(5r + 45) - (2 - 2r)=1
Imagine that the minus is like saying + -1.
(5r + 45) + -1(2 - 2r)=1
Multiply/Distribute the -1
(5r + 45) + (-2 + 2r)=1
Now that everything in the paranthesis is solved and all multiplication is done we can add and subtract.
5r + 45 - 2 + 2r =1
Group/Reorder the terms!
45 - 2 + 5r + 2r = 1
Combine like terms
43 - 7r = 1
-7r = -42
r = -42 ÷ -7
Two negatives cancel
r = 6
