Answer:
A: x = -4
B: a = -7 (I'm assuming the '-' in front of 49 was supposed to be an '=')
Explanation:
A: You need to group the like terms together, and isolate the variable, which in this case is x.
Take the 7 over to the other side, so the equation looks a little bit like this.
3-7 = x.
3-7 is -4, so we've gotten our answer.
x = -4.
B: -7a = 49.
When two negative numbers are multiplied together, the product becomes positive.
49 is 7x7.
-7 times -7 would be 49.
So, in this situation, a would be -7.
a = -7.