-4x+6y=-18 and y=-2x+21

(9, 3)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right  

Distributive Property

Equality Properties

Multiplication Property of Equality Division Property of Equality Addition Property of Equality Subtraction Property of Equality

Algebra I

Coordinates (x, y)Solving systems of equations using substitution/elimination

Step-by-step explanation:

Step 1: Define Systems

-4x + 6y = -18

y = -2x + 21

Step 2: Solve for x

Substitution

Substitute in y [1st Equation]:                                                                           -4x + 6(-2x + 21) = -18[Distributive Property] Distribute 6:                                                                 -4x - 12x + 126 = -18[Subtraction] Combine like terms:                                                                   -16x + 126 = -18[Subtraction Property of Equality] Subtract 126 on both sides:                     -16x = -144[Division Property of Equality] Divide -16 on both sides:                               x = 9

Step 3: Solve for y

Substitute in x [2nd Equation]:                                                                         y = -2(9) + 21Multiply:                                                                                                             y = -18 + 21Add:                                                                                                                   y = 3

Where's the rest of the