Arthur D. answered 04/25/20
Forty Year Educator: Classroom, Summer School, Substitute, Tutor
3^(1-7x)=7^x
ln3^(1-7x)=ln7^x
(1-7x)ln3=xln7
(1-7x)/x=ln7/ln3
(1-7x)/x=1.9459/1.0986
(1-7x)/x=1.77125
1-7x=1.77125x
1=7x+1.77125x
1=8.77125x
x=1/(8.77125)
x=0.114
check:
3^(1-.798)=7^(0.114)
3^(0.202)=7^(0.114)
1.24847≈1.24836