If Bill’s weight is B and Tommy’s weight is T, you can set up these
equations using the given information:
B + T = 250
B = 3T + 10
Substitute 3T + 10 for B in the first equation to get:
3T + 10 + T = 250
4T + 10 = 250
4T = 240
T = 60 Tommy weighs 60 lb, which is C.