inverse function for arcsin

I have a webworks problem that I am not doing correctly. here it is

f(x)=arcsin(x/7)+10

This is what I did. Y=arcsin(x/7)+10

X=arcsin(y/7)+10

x-10=arcsin(y/7)

y/7=arcsin^-1(x-10)

answer y=7*arcsin^-1(x-10)

the answer is supposed to be in this form, webworks said this is incorrect. I did the rest of the problems this way but they were tan and cos and I am sure this one must be done differently or I must have skipped or omitted something. Please let me know if you can help me understand how this one is solved.

Thank you!

keith stevens

keithstevens@ctc.net