Question

Given that 4x-5y = 21 Find x when y = -4. Give your answer as a fraction in its simplest form.

Answer 1

Answer:

x = 1/4

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Equality Properties

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

Step-by-step explanation:

Step 1: Define

Identify

4x - 5y = 21

y = -4

Step 2: Solve for x

1. Substitute in y:                                                                                                  4x - 5(-4) = 21
2. Multiply:                                                                                                             4x + 20 = 21
3. [Subtraction Property of Equality] Subtract 20 on both sides:                      4x = 1
4. [Division Property of Equality] Divide 4 on both sides:                                  x = 1/4

Answer 2

Answer:

1/4 (One over Four)

Step-by-step explanation:

Step 1. Multiply -5 with -4 (Negitive x Negitive is always Positive!).

Step 2. Subtract 20 (From step 1) from 21.

Step 3. divide 4x by 1.