Determine whether the equation represents a linear function. y= -x (exponent 2)

giving brainliest to whoever shows work

Pls the last one and it has to be like number 6

Agroup of five people go out to eat and buy appetizers and main dishes they decide to split the bill so each person pays 20% of the total cost appetizers are $5 and main dishes are $10 write an expression to show how much each person pays explain it with how to solve the problem

To start to solve the system of equations below, which number would you multiply in the equation -2x-5y=-1? the two equations are -2x-5y=-1 and 4x+2y=8