If the answer is 1-2/3m what is the question>

Question

How can you solve equations like these?

9r + 7 = 4r - 8

Need to get the r on one side.
1st- subtract 4r from the right side of the = sign. What you do to one side do to the other. 9r-4r+7=4r-4r-8. 5r+7=-8
2nd- subtract 7 from the left side to get r's by themselves. 5r+7-7=-8-7....5r=-15.
Divide 5r by 5.....remeber do it to both sides......5r/5=-15/5......r=-3
check answer.
9(-3)+7=4(-3)-8....-27+7=-12-8............-20=-20

Thanks for your help. I'm completely lost. Can you explain how 9r+7 = 4r-8?

Answer 1

r=-3

Answer 2

4.9u+5.87=23.81

Answer 3

what is rule for input value of n?