We are given the equation $7 - \frac{k}{4} = \frac{k}{10}$ and asked to solve for the variable $k$.

AlgebraLinear EquationsSolving EquationsFractionsVariable IsolationArithmetic Operations
2025/7/20

1. Problem Description

We are given the equation 7k4=k107 - \frac{k}{4} = \frac{k}{10} and asked to solve for the variable kk.

2. Solution Steps

First, we want to isolate the terms with kk on one side of the equation. Add k4\frac{k}{4} to both sides of the equation:
7k4+k4=k10+k47 - \frac{k}{4} + \frac{k}{4} = \frac{k}{10} + \frac{k}{4}
7=k10+k47 = \frac{k}{10} + \frac{k}{4}
Next, we need to find a common denominator for the fractions k10\frac{k}{10} and k4\frac{k}{4}. The least common multiple of 10 and 4 is
2

0. So, we rewrite the fractions with a denominator of 20:

k10=2k20\frac{k}{10} = \frac{2k}{20}
k4=5k20\frac{k}{4} = \frac{5k}{20}
Now substitute these into the equation:
7=2k20+5k207 = \frac{2k}{20} + \frac{5k}{20}
7=2k+5k207 = \frac{2k + 5k}{20}
7=7k207 = \frac{7k}{20}
To solve for kk, we can multiply both sides of the equation by 20:
720=7k20207 \cdot 20 = \frac{7k}{20} \cdot 20
140=7k140 = 7k
Finally, divide both sides by 7 to isolate kk:
1407=7k7\frac{140}{7} = \frac{7k}{7}
20=k20 = k
So, k=20k = 20.

3. Final Answer

The final answer is k=20k = 20.