Answer: 238 lbs
Explanation:
x = joe's weight
y = joe's dad's weight
x + y = 336
y = x +140
Substitute for y
x + x + 140 = 336
2x + 140 =336
2x = 196
x = 98
Joe weighs 98 lbs
Now, plug that into Joe's dad's weight equation
y = 98 + 140
y = 238
Joe's dad weighs 238 lbs