How many ounces of a 19% alcohol solution and a 37% alcohol solution must be combined to obtain 90 ounces of a 24% solution

19% alcohol solution = 65 ounces

37% alcohol solution = 25 ounces

Step-by-step explanation:

Let

19% alcohol solution = x

37% alcohol solution = y

x + y = 90 (1)

0.19x + 0.37y = 90*0.24

0.19x + 0.37y = 21.60 (2)

from (1)

x = 90 - y

Substitute into (2)

0.19x + 0.37y = 21.60

0.19(90-y) + 0.37y = 21.60

17.1 - 0.19y + 0.37y = 21.60

- 0.19y + 0.37y = 21.60 - 17.1

0.18y = 4.5

y = 4.5/0.18

y = 25 ounces

x + y = 90 (1)

x + 25 = 90

x = 90 - 25

x = 65 ounces

The answer is in the image 

Cost of 7 gallons=$24.50

Cost of 1 gallon=24.50/7=3.5

Cost of 15 gallons=15*3.5=52.5

Cost of 15 gallons will be $52.5

The answer is in the image 

The total nom of  code that can be used is equal to 5+3 = 8

For every 8 cars there are 7 trucks

Therefore,

Cars:Truck=8:7

Answer is B)8:7

The answer is in the image 

Salesperson will make 6% of 1800

=(6/100)*1800

=108

Salesperson will make $108 in $1800 sales

The solution is given in the image below

Here,

tip=18%of $32

tip=(18/100)*32

=0.18*32

=$5.76

Total payment=32+5.76=$37.76