Question

Yuson used her calculator to solve the equation

4/5x−8=3. She entered the following on her screen and got an incorrect answer. How could she use parentheses to find the correct​ answer? Explain. What is the correct​ answer?

Answer 1

x = 55/4.

Explanation:

4/5x - 8 = 3

(4/5) x - 8 = 3

Add 8 to both sides:

(4/5)x = 11

Next, to isolate x, we multiply both sides by 5/4:

(5/4)(4/5)x = 11 * 5/4

1x = 55/4.

Answer 2

Rather than just multiplying 5/4 with 8, she has to multiply it with 3 + 8. She could put parentheses around the 3 + 8, according to PEMDAS, this would mean that the parenthesis must be solved before multiplication. The correct answer would be:

4/5x - 8 = 3

4/5x = 3 + 8

x = (3 + 8)5/4

x = 11 x 5/4

x = 55/4 or 13.75