Easy equation confusing me

[jacket882]

ok so i got this:

c = 0.1 (r - 50,000)
1.2c = 0.1 (1.25r - 50,000)

can someone solve it for c and r and list the steps - its elementary but my answer is not making sense

[derricklim]

Gosh, I can't get it done either!

[Ian Stewart]

ok so i got this:

c = 0.1 (r - 50,000)
1.2c = 0.1 (1.25r - 50,000)

can someone solve it for c and r and list the steps - its elementary but my answer is not making sense

The decimals complicate matters. You could make things at least a bit easier by first multiplying each equation by 10 on both sides:

10c = r - 50,000
12c = 1.25r - 50,000

We now can multiply the first equation by 6, the second by 5, and subtract the second equation from the first:

60c = 6r - 300,000
60c = 6.25r - 250,000
0 = -0.25r - 50,000
50,000 = -0.25r
-200,000 = r

Plugging that value back in to one of our equations:

10c = -200,000 - 50,000
10c = -250,000
c = -25,000

[jacket882]

thanks for that

Its actually quite confusing because the revenue and commission cannot be negative - and those are definitely the equations I was given to calculate -

Carla earns a base salary of $30,000 plus 10% commission on her total sales revenue exceeding $50,000. How much did she make on commission this year given that if her total sales revenue had been 25% higher, her commission would have been 20% higher?

edit: oh wait I think its negative because those are the values she got under what she could have made.. I think

[Ian Stewart]

thanks for that

Its actually quite confusing because the revenue and commission cannot be negative - and those are definitely the equations I was given to calculate -

Carla earns a base salary of $30,000 plus 10% commission on her total sales revenue exceeding $50,000. How much did she make on commission this year given that if her total sales revenue had been 25% higher, her commission would have been 20% higher?

edit: oh wait I think its negative because those are the values she got under what she could have made.. I think

No, you're looking at a dodgy question. If her revenue goes up by 25%, her commission-eligible revenue will go up by more than 25%. So the numbers don't make sense. Not sure what the source is, but I imagine they intended the numbers to be reversed: that is, they likely meant if her revenue were 20% higher, then her commission would have been 25% higher.