21 – (13 +4) = y +18

Answer 1

-14

order of operations is PEMDAS,

parentheses first, then exponents, multiplication, division, adding, and last subtraction.

follow that method, you get y=-14

Answer 2

Order of Operations - PEMDAS

1. Parentheses
2. Exponents
3. Multiplication/Division
4. Addition/Subtraction

Following this order, we can simplify the left side of the equation.

1. First simplify inside the parentheses --> 13+4 = 17
2. Our new equation is 21 - 17 = y + 18
3. The only remaining operation on the left is subtraction.
4. Since 21-17 = 4, our new equation is 4 = y + 18

We now know that y + 18 = 4, but we need to know what why equals.

1. Since the opposite of addition is subtraction, we can subtract 18
2. y + 18 - 18 = y
3. Imagine two identical baskets with 10 apples each.
4. If you take away 2 apples from one basket but not the other, are the baskets still equivalent?
5. They aren't because one basket only has 8 apples and the other basket still has 10
6. How could we make them equivalent? What if we took away 2 apples from the second basket also?
7. Now both baskets have the same amount (8) of apples.
8. In similar fashion, if we took 18 away from the right to get y by itself, we also have to take 18 away from the left.
9. Recall our equation at this point is 4 = y + 18
10. If we subtract 18 from both baskets to preserve equality: 4 - 18 = y + 18 - 18
11. Which simplifies to -14 = y

Answer 3

Hi Nick!

21 – (13 +4) = y +18

For easier understanding. take those numbers out of the parenthesis, by multiplying it by (-1).

21 – 13 - 4 = y +18

Subtract those numbers on the left side.

4 = y +18

Subtract 18 on the left side in order to isolate the variable, y.

-14 = y

Answer 4

Hi, Nick,

21 – (13 +4) = y +18

21 - (17) = y + 18

4 = y + 18

4 - 18 = y

y = -14

Bob