Use a half-angle identity to find the exact value of tan 105 degrees I have 30 minutes...please help.

Fawn bought a total of 70 cakes for a tea party. she spent $3,025. fawn bought vanilla cakes for $22 each and a fruit filled cake for $55 each. the system of equations below can be used to find the number of vanilla cakes, v, and the number of fruit filled cakes, f, fawn purchased. which system of equations has the same solution as the system below.