How do i add and subtract unlike fractions

You add and subtract unlike fractions by finding a common denominator, which is basically the LCM (Least Common Multiple) of the two numbers. Then, once the two fractions have the same base, you can straight up add the numerators, and if possible, simplify. Here are some examples:
1/5 + 3/10 = ?
Denominators = 5, 10
What is the LCM?
=> 10
Therefore...
1/5 × (2/2) + 3/10 = ? (The paranthesis next to 1/5 shows how we are creating a common denominator)
2/10 + 3/10 = ?
= 5/10
= 1/2 (Simplify)
Hope this helped and have a phenomenal day!