The value of x is about 4.7
The explicit formula for calculating the sum is

The sum of the nth term of a sequence is expressed as;

a is the first term
d is the common difference
n is the number of terms
For the sequence 0 + 1 + 2 + 3 +...

Similarly for the sequence:
1 + 2+ 3 + 4+...

Taking the product of the sum to get the explicit formula for calculating the sum

Learn more here: brainly.com/question/24547297
Well the factors of "72" is→ 1,2,3,4,6,8,9,12,18,24,36,72
To find the factor(s) "72" just write out the muliples that equals 72
let's common be "x" 8x add 5x equal to 13 x now x equal to 26 devise 13 equal to 2,. so ans is 2