A fraction represents a part of a whole, consisting of a numerator (top number) and a denominator (bottom number). A decimal is a number expressed in the scale of tens, using a decimal point.
To convert a fraction to a decimal, divide the numerator by the denominator. If the division ends (like 3/4 = 0.75), it is a terminating decimal. If it repeats indefinitely (like 1/3 = 0.3333...), it is a repeating decimal.
Write down the decimal divided by 1 (e.g. 0.75/1). Multiply both top and bottom by 10 for every number after the decimal point (e.g. 75/100). Simplify the fraction by dividing both top and bottom by their greatest common divisor (GCD).