A boy does [tex]\frac{1}{4}[/tex] of his homework exercises in the evening and [tex]\frac{2}{3}[/tex] of them in the morning. He is still left with two exercises. How many exercises did he have for homework?



Answer :

To determine the total number of homework exercises the boy had, let's denote the total number of exercises by [tex]\( x \)[/tex].

According to the problem:

1. The boy does [tex]\( \frac{1}{4} \)[/tex] of his total exercises in the evening.
2. He does [tex]\( \frac{2}{3} \)[/tex] of his total exercises in the next morning.
3. After doing these exercises, he is still left with 2 exercises.

Let's express these pieces of information mathematically:

1. Exercises done in the evening: [tex]\( \frac{x}{4} \)[/tex]
2. Exercises done in the morning: [tex]\( \frac{2x}{3} \)[/tex]
3. Remaining exercises: 2

Since the total number of exercises [tex]\( x \)[/tex] is the sum of the exercises done in the evening, the exercises done in the morning, and the remaining exercises, we can set up the following equation:

[tex]\[ \frac{x}{4} + \frac{2x}{3} + 2 = x \][/tex]

We'll solve this equation step-by-step:

1. Find a common denominator for the fractions [tex]\( \frac{x}{4} \)[/tex] and [tex]\( \frac{2x}{3} \)[/tex], which is 12.

[tex]\[ \frac{x}{4} = \frac{3x}{12} \quad \text{and} \quad \frac{2x}{3} = \frac{8x}{12} \][/tex]

2. Substitute these into the equation:

[tex]\[ \frac{3x}{12} + \frac{8x}{12} + 2 = x \][/tex]

3. Combine the fractions on the left side:

[tex]\[ \frac{3x + 8x}{12} + 2 = x \implies \frac{11x}{12} + 2 = x \][/tex]

4. To clear the fraction, multiply every term by 12:

[tex]\[ 11x + 24 = 12x \][/tex]

5. Solve for [tex]\( x \)[/tex] by isolating [tex]\( x \)[/tex] on one side:

[tex]\[ 12x - 11x = 24 \implies x = 24 \][/tex]

So, the total number of exercises he had for homework is [tex]\(\boxed{24}\)[/tex].