### Instruction: Find: $\frac{12}{30}-\frac{1}{7}$.### Response: To subtract fractions, I need a common denominator.
The least common multiple of 30 and 7 is 210, so I will multiply the first fraction by $\frac{7}{7}$ and the second fraction by $\frac{30}{30}$.
This gives me: $\frac{84}{210}-\frac{30}{210}$.
Now I can subtract the numerators and keep the denominator: $\frac{84-30}{210}=\frac{54}{210}$.
I can simplify this fraction by dividing both the numerator and the denominator by 6: $\frac{54}{210}=\frac{9}{35}$.