Let's represent the unknown number with Y
So it says 5 times the sum of Y plus 3 equals 8 times Y minus 9
That is represented as;
5(Y+3)=8Y-9
First of all, multiply 5 by what is in the bracket. That will be 5Y+15
(5 times Y is 5Y and 5 times 3 is 15)
Therefore;
5Y+15=8Y-9
Collect like terms. So -9 will go over the equality sign to become +9. The same applies to 5Y
15+9=8Y-5Y
24=3Y
Divide both sides by 3
24 divided by 3 is 8. So Y= 8
The number is 8 which is B
