# Math Help - percentages forumla - method to solve?

1. ## percentages forumla - method to solve?

I've forgotten how to do math! It's been so long... this is embarassing. I have an amount of money, $7000 for example, that is the total amount spent for an advertising campaign. The campaign total cost includes the cost of the ads, and then the agency fee which is 20% of the cost of the ads. X = total cost of campaign B = cost of ads C = 20% of B B + ( .2 x B) = 7000 how would I use a forumla to calculate this? Would anyone be able to send me some links or point me in the right direction? 2. Originally Posted by v098646 I've forgotten how to do math! It's been so long... this is embarassing. I have an amount of money,$7000 for example, that is the total amount spent for an advertising campaign. The campaign total cost includes the cost of the ads, and then the agency fee which is 20% of the cost of the ads.

X = total cost of campaign
C = 20% of B

B + ( .2 x B) = 7000

how would I use a forumla to calculate this? Would anyone be able to send me some links or point me in the right direction?
$B+0.2B=7000$

$B(1+0.2)=7000$

$B(1.2)=7000$

$B=\frac{7000}{1.2}=\frac{10(7000)}{12}$

That's how much you have at most to spend on the adverts.

$C=\frac{20}{100}\ \frac{10(7000)}{12}=\frac{2(7000)}{12}$

That's the agency's fee.

3. Great! I really appreciate the help. I remember now, that the way to solve these is to substitute a number (1) for one of the unknowns.