2x + 5y = 15 8x + 4y = 8

(-5/8, 13/4)

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Equality Properties

Algebra I

Solving systems of equations using substitution/eliminationSolving systems of equations by graphing

Step-by-step explanation:

Step 1: Define systems

2x + 5y = 15

8x + 4y = 8

Step 2: Rewrite systems

8x + 4y = 8

Subtract 8x on both sides:                    4y = 8 - 8xDivide 4 on both sides:                         y = 2 - 2x

Step 3: Redefine systems

2x + 5y = 15

y = 2 - 2x

Step 4: Solve for x

Substitution

Substitute in y:                    2x + 5(2 - 2x) = 15Distribute 5:                         2x + 10 - 10x = 15Combine like terms:           -8x + 10 = 15Isolate x term:                     -8x = 5Isolate x:                              x = -5/8

Step 5: Solve for y

Define original equation:                    2x + 5y = 15Substitute in x:                                     2(-5/8) + 5y = 15Multiply:                                                -10/8 + 5y = 15Simplify:                                                -5/4 + 5y = 15Isolate y term:                                      5y = 65/4Isolate y:                                               y = 13/4

Step 6: Graph systems

Check the solution set.

The solution set is equivalent (is in decimal form).