Question

log(x,81)+log(x,9)+log(x, 3)=7

Answer 1

$log_{x}81 + log_{x}9 + log_{x}3 = 7 \\ log_{x}(81 \times 9 \times 3) = 7 \\ log_{x}( {3}^{4} \times {3}^{2} \times 3) = 7 \\ log_{x} {3}^{7} = 7 \\ 7 log_{x}3 = 7 \\ log_{x}3 = 1 \\ x = 3$