Answer :
110x=405
1*x^2 +1*x^1 +0*x^0=4*5^1+0*5^0
x^2+x=4*5
x^2+x=20
x^2+x-20=0
x^2 +5x-4x-20=0
x(x+5)-4(x+5)=20
(x-4)(x+5)=20
x= 4 or -5
But a base cannot be negative so
x=4
110x=405
1*x^2 +1*x^1 +0*x^0=4*5^1+0*5^0
x^2+x=4*5
x^2+x=20
x^2+x-20=0
x^2 +5x-4x-20=0
x(x+5)-4(x+5)=20
(x-4)(x+5)=20
x= 4 or -5
But a base cannot be negative so
x=4