Answer:
67%
Step-by-step explanation:
First of all, we must find the decrease;
39 - 13
=26
Then we can find the percentage decrease
26/13 ×100 =66.666..which can be written as 67.
If you mean added together 3 times then it would be 6 3/4 and just in case this sounds rude I do not want it to be.
Here is a trick that not a lot of people know
(# of terms)*(first+last)/2
(in case you don't know, * means multiply and / means divide)
First you would isolate (7m) by subtracting 4 from both sides:
4 + 7m - 4 = 5 - 4
This would leave you with:
7m = 1
Then you would isolate m by dividing both sides by 7:
7m/7 = 1/7
Your final answer:
m = 1/7