Question

5 ^{x+1} -5^{x-2} =620

Answer 1

5^(x+1)-5^(x-2)=620
5*5^x-5^x/5^2=620
5^3*5^x-5^x=620*5^2
5^x*(125-1)=15500
5^x=15500/124
5^x=125
5^x=5^3
x=3