Can someone explain this to me? i really don't understand

Nine more than four times a number is the same as one less than twice the number. find the number?

Given that sin∅ = 1/4, 0 < ∅ < π/2, what is the exact value of cos∅? a. (√4)/4 b. (√15)/4 c. (4π)/2 d. (4√2)/4

Determine if the sequence is arithmetic or geometric.  then identify the next term in the sequence.    0.2, 1, 5, 25, . . group of answer choices arithmetic; 75 geometric; 75 arithmetic; 125 geometric; 125