What do you need help with specifically? When multiplying fractions you just multiply across. 2/3 * 4/5 = 8/15 (and simplify if needed). When dividing fractions you do the same as multiplying except flip the second fraction. So 2/3 will be the same and 4/5 will be 5/4 and then you multiply and simplify if needed. (Tip: a way to remember the division is leave me, change me, and turn me over). I hope that helps!

Think about it this way.

A decimal is the most simple form of a value. Such as: 0.125.

A fraction is a less simplified version of the same value. Hence: 1/8.

The two are equal. A fraction is made of a numerator and denominator. It looks like 1/8 and reads as (numerator of 1) divided by: (denominator of eight). The fraction is equal to the value that can go into 1 8 times exactly. 

The decimal value is the value as it is. 0.125 can go into 1 8 times exactly, such, 0.125 is, or =, 1/8.

To multiply a fraction value by another fraction value, you find what quantity can enter a value a by a certain quantity. To put that much simpler, I will present an example: 1/8(1/4)= ?

This situation is as such: We must find what value enters 1/8 four times. This is shown by the numerator of 1/4 relevant to the denominator by action of division as a whole being split into four equal parts. This is relevant to to 1/8 by being of 1/8(multiplication means of). 1/4 of 1/8 is 1/8 being split into four equal parts and us surveying the value of any one of these parts. what value is equal to that of 14 of 1/8? 1/32 is this value. How? when a value enters into 1 32 times exactly, its total value is 1/32 of 1. if you multiply this value by four, which is the reverse process of dividing, you find a value that enters 1 a total of eight times. Like a group of 72 people. 1/8 of this would be 9 people, as 9 people would fit the original value of this situational group 8 times. 9 is 1/8 of 72. 1/32 is 1/4 of 1/8.

When you multiply a fraction to something, you multiply the numerator together and also the denominators. 1/8*1/4 is 1*1/2*8. hence, 1/32. Meditate on this and think of why this is until you are fully certain you understand exactly why mathematics is this way.

If you are done, congrats! you understand fractions. Also, you just thought critically. Cool!