PLEASE HELP FAST! Solve for Y in the following system of equations! X-y=-1
3x+5y=21
A.) 2
B.) 3
C.) 9
D.) 12

B.) 3

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/elimination

Step-by-step explanation:

Step 1: Define Systems

x - y = -1

3x + 5y = 21

Step 2: Rewrite Systems

x - y = -1

Add y to both sides:                    x = y - 1

Step 3: Redefine Systems

x = y - 1

3x + 5y = 21

Step 4: Solve for y

Substitution

Substitute in x:                              3(y - 1) + 5y = 21Distribute 3:                                   3y - 3 + 5y = 21Combine like terms:                     8y - 3 = 21Add 3 to both sides:                     8y = 24Divide 8 on both sides:                y = 3

Ibelieve it's a. 2.2 - x = -10.85 (plz tell me if it's right : ) )