Answer:
He must earn $2,400 to cover both leisure and $2,160 for school expenses.
Step-by-step explanation:
Let the total amount Ken must earn be k. Then 10% of that would cover leisure activities and the remaining 90% specifically for school expenses.
Then 0.90k = $2,160, and k = $2,400.
He must earn $2,400 to cover both leisure and $2,160 for school expenses.
Answer:
(A) Your friend will save $282.
(B) Your friend will get 23.5% off the original price of the mattress.
Step-by-step explanation:
We first need to find out the price of the mattress after the 15% discount. Our first step is to find what 15% of 1,200 is. We can do this by multiplying the two numbers.
1,200 x 15% -----> 1,200 x 0.15= 180.
15% of $1,200 is $180.
Next subtract $180 from $1,200, which equals $1,020. We can now apply the 10% off internet coupon.
1,020 x 10% ------> 1,020 x 0.10= 102.
10% of $1,020 is $102.
Next we subtract $102 from $1,020 and we get $918, the final price of the discounted mattress.
We subtract to see how much money the friend saved.
$1,200 - $918= $282.
We can get the percentage by dividing $282 by $1,200.
282 / 1200= 0.235 decimal form ----> 23.5%
so we have the points of (0,-7),(7,-14),(-3,-19), let's plug those in the y = ax² + bx + c form, since we have three points, we'll plug each one once, thus a system of three variables, and then we'll solve it by substitution.
well, from the 1st equation, we know what "c" is already, so let's just plug that in the 2nd equation and solve for "b".
well, now let's plug that "b" into our 3rd equation and solve for "a".
![\bf -19=9a-3b-7\implies -12=9a-3b\implies -12=9a-3(-1-7a) \\\\\\ -12=9a+3+21a\implies -15=9a+21a\implies -15=30a \\\\\\ -\cfrac{15}{30}=a\implies \blacktriangleright -\cfrac{1}{2}=a \blacktriangleleft \\\\[-0.35em] ~\dotfill\\\\ \stackrel{\textit{and since we know that}}{-1-7a=b}\implies -1-7\left( -\cfrac{1}{2} \right)=b\implies -1+\cfrac{7}{2}=b\implies \blacktriangleright \cfrac{5}{2}=b \blacktriangleleft \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill y=-\cfrac{1}{2}x^2+\cfrac{5}{2}x-7~\hfill](https://tex.z-dn.net/?f=%5Cbf%20-19%3D9a-3b-7%5Cimplies%20-12%3D9a-3b%5Cimplies%20-12%3D9a-3%28-1-7a%29%20%5C%5C%5C%5C%5C%5C%20-12%3D9a%2B3%2B21a%5Cimplies%20-15%3D9a%2B21a%5Cimplies%20-15%3D30a%20%5C%5C%5C%5C%5C%5C%20-%5Ccfrac%7B15%7D%7B30%7D%3Da%5Cimplies%20%5Cblacktriangleright%20-%5Ccfrac%7B1%7D%7B2%7D%3Da%20%5Cblacktriangleleft%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%5Cstackrel%7B%5Ctextit%7Band%20since%20we%20know%20that%7D%7D%7B-1-7a%3Db%7D%5Cimplies%20-1-7%5Cleft%28%20-%5Ccfrac%7B1%7D%7B2%7D%20%5Cright%29%3Db%5Cimplies%20-1%2B%5Ccfrac%7B7%7D%7B2%7D%3Db%5Cimplies%20%5Cblacktriangleright%20%5Ccfrac%7B5%7D%7B2%7D%3Db%20%5Cblacktriangleleft%20%5C%5C%5C%5C%5B-0.35em%5D%20%5Crule%7B34em%7D%7B0.25pt%7D%5C%5C%5C%5C%20~%5Chfill%20y%3D-%5Ccfrac%7B1%7D%7B2%7Dx%5E2%2B%5Ccfrac%7B5%7D%7B2%7Dx-7~%5Chfill)
Rate for Sally is 1 room per 8hrs
rate for Steve is 1 room per 7hrs
combined rate:
1/8 + 1/7 = 1/T
7/56 + 8/56 = 1/T
15/56 = 1/T
56/15 = T
3 11/15 = 3 hrs 44 min
