Verifying parallel lines
can somebody explain this to me

Irene bought 3 yards of fabric and a spool of thread for $28.10. if the spool of thread cost $1.25, how much did the fabric cost per yard?

Find an equation of the line perpendicular to the graph of 28x-7y=9 that passes through the point at (4,1)

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36