The math club is doing a fundraiser to raise money to attend a math competition. The club was told by their advisor to raise $2000, but they decided to raise $4000. The club is selling " I like TT" T-shirts for $10 and "i like TT" sweaters for $20. let x equal the number of T-shirts sold and let y equal the number of sweatshirts sold.

Write a linear equation to represent raising $4000.
and
Are the graphs of the equations parallel? How can you tell?