Respuesta :

Answer:

a=5

Step-by-step explanation:

You'll want to expand the -4(a-5) first.  That'll be :

-4a+20.  

So 2a-4a+20=10.  

Variables on the left, plain numbers on the right:

2a-4a=10-20

-2a=-10

-a=-5

a=5

Done.