6th grade math help me please

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?

Jada has a meal in a restaurant she adds up the prices listed on the menu for everything they ordered and gets a subtotal of $42.00. when the check comes, it says they also need to pay $3.99 in sales tax. what percentage of the subtotal is the sales tax

Choose the linear inequality that describes the graph. the gray area represents the shaded region. a: y ≤ –4x – 2 b: y > –4x – 2 c: y ≥ –4x – 2 d: y < 4x – 2