Respuesta :

309445

Answer:

a=−b−c−d+15

Step-by-step explanation:

Step 1: Add -b to both sides.

a+b+c+d+−b=15+−b

a+c+d=−b+15

Step 2: Add -c to both sides.

a+c+d+−c=−b+15+−c

a+d=−b−c+15Step 3: Add -d to both sides.

a+d+−d=−b−c+15+−d

a=−b−c−d+15