Answer:
150
Explanation:
So I will shorten Eric, and Bob's names as E, and B.
So the equations are this
B-E = B+E - 240, E as Eric, and B as Bob, and this E+B=9(E-B)
Move the variables and you get
-2E =- 240
Just divide them both by -2
and E=120
So when we know the value of E we can just plug it into the 1st question
120+B=9B+1080
Moves the Variables and numbers to the other side
8B=1200
1200/8= 150
B=150
There is Bob's weight