Question 1132826
s = the number of goals sam scored.
a = the number of goals alex scored.


your equations are:


s + a < 9
a = s + 3


replace a with s + 3 in the first equation to get s + s + 3 < 9
combine like terms to get 2s + 3 < 9
subtract 3 from both sides to get 2s < 6
divide both sides by 2 to get s < 3


sam scored less than 3 goals.
that means sam scored 0 or 1 or 2.
alex scored 3 more than sam.
that means alex scored 3 or 4 or 5.


together they scored 3 or 5 or 7.


your solution is that alex scored 3 or 4 or 5 goals.


sam could not have scored 3 goals, because then alex would have had to score 6 and 3 + 6 is equal to 9 which is not smaller than 9.