Answer :
Answer:
a=5
Step-by-step explanation:
3a-5b=10
a+7b=12
multiply the second row with -3
-3a-21b=-36 now we gonna add this to the first row
3a-5b=10
_________+
-26b=-26 b=1 now we gonna put in one of the equations to find a
a+7b=12
a+7.1=12 a=5