Question 24154
first you must remember you are trying to get the variable alone on one side and the numbers alone on the other.  If the variable is being divided then you must multiply to get rid of the number with the variable and vise versa.  Understand?  Same and when you add to get rid of a neg. number...
so in your equation

2/5x=3(-5)  the first thing to do is mult the 3 to the -5 and you have
2/5x=-15    then you multiply both sides by 5 to get rid of the fraction
5*2/5x=-15*5
2x=-30      now you must divide each side by 2 
x=-15

do you see how I got your solution? If you have any trouble, please let me know.

a.