Question 530826
By observation, we can say that Sue has 7 and Manuel has 6.
.
Algebraically, we can show this is true.
.
x = Sue's trains
y = Manuel's trains
.
x + y = 13
so
x = 13-y
.
x = y + 1  (given)
.
x = x
so
13-y = y +1
12 = 2y
2y = 12
y = 6
.
x = y+1
x = 7
.
Done.