Say you have the equation 5(5x+7)=155
First you multiply 5 by everything in the parenthesis so you get 25x+35=155 then subtract 35 from both sides and get 25x=120 then 120 divided by 25 equals 4.8 so x=4.8
A simple answer is because 4 and 5/4 is equal to 5 and 1/4. Because 5/4 is 1/4 more than 4/4, or 1.
13. Because it can't be divided by a whole number except 1 and itself. 14 can be Divided by 2. 21 and 33 can be divided by 3 making them composite or divisible by more than just 1 and itself :)
You get 2m+m-3n which simplifies to 3m-3n