Question

Factor 30 - 5y

Answer 1

5(6-y)

Answer 2

We can't do much here, but the thing we can do is take "common factor".
"Common factor" is a reverse step from the distributive axiom in arithmetics, wich states that if a number multiplies the sum of other two, it's the same as the sum of each number multiplicating the outside individually, visually written like this:
\[a(b+c)=ab+ac\]
So therefore, "common factor" would be more a, "if the operation of two or more numbers wich have a multiple in common, it's the same as the multiple multiplying the sum of the both numbers divided by the multiple"
more visually:
\[a.c \pm a.b=a(c \pm b)\]
so, for the problem in question:
30-5y
We can clearly see that 5 actually is a multiple of 30, so all I do is take it as common factor, and divide both numbers by 5:
\[30-5y=5(\frac{ 30 }{ 5 }-\frac{ 5y }{ 5 })\]
30/5=6 and 5/5=1, therefore:
\[30-5y=5(6-y)\]
so we conclude that it's factored form is:
\[5(6-y)\]