Challenge  At a​ party, the amount of people who ate meatballs was 11 less than four fifths

of the total number of people. The number of people who ate meatballs was 65. Write and solve an equation to find the number of people at the party. Let x represent the number of people at the party. Use pencil and paper. Write a​ one-step equation that has the same solution.
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Part 1
Write an equation that represents the number of people at the party.

65
four fifths
11
xminus

four fifths
11
65
equals

65
11
four fifths

1 answer

To solve this problem, we start with the information provided. We know that the number of people who ate meatballs (which is given as 65) is 11 less than four-fifths of the total number of people at the party (which we will denote as \( x \)).

Let's break down the statement mathematically:

  1. Four-fifths of the total number of people is represented as \( \frac{4}{5}x \).
  2. Eleven less than that value is represented as \( \frac{4}{5}x - 11 \).

According to the problem, this is equal to the number of people who ate meatballs, which is 65. Therefore, we can set up the following equation:

\[ \frac{4}{5}x - 11 = 65 \]

Now, to solve for \( x \):

  1. Add 11 to both sides of the equation:

\[ \frac{4}{5}x - 11 + 11 = 65 + 11 \] \[ \frac{4}{5}x = 76 \]

  1. Next, multiply both sides by the reciprocal of \( \frac{4}{5} \) to solve for \( x \):

\[ x = 76 \cdot \frac{5}{4} \]

  1. Calculate \( 76 \cdot \frac{5}{4} \):

\[ x = 76 \cdot 1.25 \] \[ x = 95 \]

Thus, the total number of people at the party is \( x = 95 \).

One-Step Equation

To write a one-step equation that has the same solution, we can isolate \( x \) in the original equation. Since we have:

\[ \frac{4}{5}x = 76 \]

We can rewrite it in a one-step form by multiplying both sides by \( \frac{5}{4} \):

\[ x = 76 \cdot \frac{5}{4} \]

This is the one-step equation, but if you prefer a more standard form to show this as a simple equation:

\[ x = 95 \]

This gives us a clear, straightforward solution for the number of people at the party.