using the multiplication principle how to solve this problem -2/5y=-14/15

Multiplication principle:
Multiplying (or dividing) the same non-zero number to both sides of an equation does not change its solution set.

So you need to multiply/divide in a way that you have the y alone on one side.

Example:
5*x=20
if you multiply with 1/5 you get:
1/5*5*x=1/5*20
<=> x=4