Question

If the same number is addedto the numbers 5,11,15, and 31,the resulting numbers are in proportion. Find the number

Answer 1

let the no. be x
5+x*31+x=11+x*15+x
155+5x+31x+x^2=165+11x+15x+x^2
165-155+26x-36x=0
10-10x=0
x=1