Algebra 1 PLEASE help
posted by 123ABC .
Roberta sold fifty tickets for the school play. Roberta sold ten more student tickets than adult tickets. How many student tickets did Roberta sell?
From this result, if the total cost of a student ticket was threefourths the cost of an adult ticket, and Roberta collected a total of 212.50, what was the total cost of a student ticket?

30x+20y=212.50
x=3/4y
20(3/4y)+20y=212.5
Go from there, and when you solve for y, put that back in the original equation at the top for x. 
what does x stand for and what does y stand for?

x=student tickets, y=adult tickets

okay.. but...20(3/4y)+20y=212.5 ... when u solve this we get a decimal... and is this equation to find the COST of a student ticket...