5x+y=9
10x-7y=-8
I need help!

(11/9, 26/9)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right  

Equality Properties

Multiplication Property of Equality Division Property of Equality Addition Property of Equality Subtract Property of Equality

Algebra I

Terms/CoefficientsSolving systems of equations using substitution/elimination

Step-by-step explanation:

Step 1: Define Systems

5x + y = 9

10x - 7y = -8

Step 2: Rewrite Systems

Manipulating: Equation 5x + y = 9

Subtract 5x on both sides:                    y = 9 - 5x

Step 3: Redefine Systems

y = 9 - 5x

10x - 7y = -8

Step 4: Solve for x

Substitution

Substitute in x:                    10x - 7(9 - 5x) = -8Distribute -7:                        10x - 63 + 35x = -8Combine like terms:           45x - 63 = -8Add 63 on both sides:        45x = 55Divide 45 on both sides:    x = 11/9

Step 5: Solve for y

Define equation:                    5x + y = 9Substitute in x:                       5(11/9) + y = 9Multiply:                                  55/9 + y = 9Isolate y:                                 y = 26/9

The answer is 1 because you have to flip the sign when dividing by negative number and 3