ANSWER
n = 2
EXPLANATION
Let 'n' be the number.
"when 90 is added to a number" is 90+n. And this equals to "46 times the number" which is 46n. The equation to solve for n is:
[tex]\begin{gathered} 90+n=46n \\ 90=46n-n \\ 90=45n \\ n=\frac{90}{45} \\ n=2 \end{gathered}[/tex]