algebraic formula question

[bribil01]

This is the question - i'm seeking the algebraic technique to solve this rather than number plugging the lowest common denominator.

Q:
Company Z spent 1/4 of its revenues last year on marketing and 1/7 of the remainder on maintenance of its facilities. What fraction of last year's original revenues did Company Z have left after its marketing and maintenance expenditures?

The formula I came up with is as followed 1/4(R) - 1/7*(1/4R) = R where R represents Revenue

If you use the correct algebraic formula and solve you should get 18/28R which equals 9/14R , i.e. 9/14 of revenue is left after marketing and maintenance.

Please help

 

[mmm4444bot]

You're close, but you goofed up in two places.

Revenue is not equal to Marketing minus Maintenance.

You're not supposed to be looking for Revenue, anyway.

This exercise asks you to write an expression that represents what's left of their revenue (R) after spending part of it on marketing and another part of it on maintenance.

This amount is:

R - Marketing - Maintenance

The second mistake that you made is writing (1/7)(1/4)R for Maintenance.

If you spend 1/4 of R on Marketing, you don't have 1/4 as the remainder. Does that make sense?

 

[Denis]

Can you follow this: 1 - [1/4 + 1/7(1 - 1/4)] ?

 

[bribil01]

thanks got it