Answer quickly please

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.

Charlie is at an amusement park that has 18 different rides. each ride costs $1.75. the function c(r) = 1.75r represents the total amount of money that charlie will spend if he goes on r rides, but he never goes on the same one more than once. what domain and range are reasonable for the function?

Given sin28.4=.4756, cos28.4=.8796, and tan28.4=.5407 find the cos of 61.6