So the question states "Allison has 5 times as many baseball cards as foot ball cards.
Lets decide that...
Base ball cards = B
and...
Foot ball cards = F
So we know there are more baseball cards than foot ball cards. In fact there is 5 times more baseball cards than there is football cards.
Lets set up our two truths.
we know these facts so far.
5F = B
F + B = 120
So the first step would be taking 5F and substituting it for B in the equation.
so....
F + 5F =120
Now right next to the F there is an imaginary 1, so you can look at it like this.
1F + 5F = 120
Now we have to add our common variables.
it becomes...
6F = 120
Then divide both sides by 6 to get F to be alone.
sooooo
6F = 120
÷6 = ÷6
*************
F = 20
Now we have the number of Football cards that Allison has. But the question is asking to find the number of Baseball cards!
So just subtract the full amount (120) minus the number of Football cards. (20)
120 - 20 = 100
So your finally answer is
Allison has 100 Base ball cards.