Write an equation and solve

Question

12 7th graders entered a contest. This was three less than five times the number of 8th graders who entered. How many 8th graders entered the contest

Answer 1

Let the number of 7th graders = 12

Let the number of 8th graders = x

 

Use these variables, we can set up an equation.

 

12 = 5x - 3

 

 

Solve the equation for x.

 

Add 3 on both sides of the equation.

 

15 = 5x

 

 

Divide both sides of the equation by 5.

 

3 = x

 

 

This means that the 8th graders who entered the contest is 3.

 

 

Answer 2

Let's use 12 for the number of 7th graders because the question says so.

 

The word "This" beginning the second sentence refers to 12 (the number of 7th graders). When it says "This was", you should think "12=" because "was" translates to an equal sign. Now, 12= what? 12= three less than five times the number of 8th graders, so let's translate the rest of it.

 

Let's use N for the number of 8th graders because we need a variable for that.

 

Five times the number of 8th graders would be 5 * N.

 

Three less than five times the number of 8th graders would be 5 * N -3.

 

Putting it all together 12 = 5 * N - 3

 

Add 3 to each side and get 15 = 5 * N

 

Divide each side by 5 and get 3 = N, so 3 8th graders entered the contest.