Question

this is a two part question.
Dylan owns a bakery where she sells cakes for $20 each, pies for $15each,and doughnuts for $2 each. Her total income,t, can be computed using the equation t=15p+2d+20c
1) solve this equation for d
t=15p+2d+20c
-15p -15p
t -15p=2d+20c
-20c -20c
t-15p-20c=2d
now divide each side by2
d=t-15p-20c/2 I stopped here but my friend went one further and did
d=t-15p/2-10c
Which is correct?

2) part 2 says Last week Dylan's total sales were $1225 not including sales tax. She knows that she sold 32 cakes and 15pies. Use the equation from
part 1 to determine how many donuts were sold last week.
d=t-15p-20c/2
d=1225-15(15)-20(32)/2
d= 1225-225-640/2
d=360/2
d=180 my friend thought this was the answer
I thought the answer was 180/2= 90
I said 90 because each was $2 so you had to divide the answer by 2 giving you 90
Can you tell me who is correct for part 1 & 2.
Thank you so much for helping us

Answer 1

d=t-15p-20c/2
is correct if you use some parentheses
d=(t-15p-20c)/2
now you won't make the mistake your friend did; you will get
d = t/2 - 15p/2 - 10c
on the other hand, if your friend got
d = (t-15p)/2 - 10c
then that's ok

On #2, d=180 is correct. That answer already includes the division by 2.
I mean, the equation said d=..., not 2d=... The answer you got was in fact d.

If you're not convinced, add it up:

180(2)+15(15)+20(32) = 360+225+640 = 1225

Answer 2

Thank you for explaining it. When I see Steve as the person answering my question I know I will get an explanation and I will understand everything better afterwards.
Thank you so much

Answer 3

aww shucks.

Reiny is also very good at explaining the solutions he provides.

Answer 4

Reiny and ms sue are also very good.