Math people plz answer the following ill give brainlest!!! solve 1/3 x =12

solve 3x + 3 =21

solve 3/2 x -4 =16

9.95 + 0.30s
the variable s stands for the number of songs downloaded. find the cost of downloading 35 songs.

write an equation and solve to find the solution to the following problem.
you have 27$ to spend at the mall and a coupon for 6$ off at your favorite store. a t-shirt costs 11$. how many t-shirts can you buy using your coupon and the money??