
notice, the 2/5 is just a "scalar" value, so you can just get the derivative of the variable part and slap the scalar as its factor.
Yes both are parts are correct
24:16 in simplest form, is.... 3:2 3 to 2
This is how you add fractions..
I have solved it step-by-step. If you understand this, you'll know how to subtract, too.
If you don't understand, message me :)