Whats the vertices with a dilation center (0,0) and a scale factor of 5/6

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c

Do one of the following, as appropriate: (a) find the critical value z subscript alpha divided by 2 , (b) find the critical value t subscript alpha divided by 2 . 99%; nequals 17; sigma is unknown; population appears to be normally distributed.

I'm confused on how to solve the triangle. can someone me ?