The number of days, d, that it will take to build a house is given by d= 720 divided by n

where n is the number of workers used each day.

Ali's company will take 40 days to build the house.

Hayley's company will take 30 days to build the house.

Hayley's company will have to use more workers each day than Ali's company.

How many more?

6 more workers

Step-by-step explanation:

The relationship between days (d) and number of workers (n) is given by the equation;

d = 720 / n

Ali's company will take 40 days to build the house.

n = 720 / d

n = 720 / 40 = 18 workers

Hayley's company will take 30 days to build the house.

n = 720 / d

n = 720 / 30 = 24 workers

Hayley's company will have to use more workers each day than Ali's company.

How many more?

24 - 18 = 6 more workers

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

Salesperson will make 6% of 1800

=(6/100)*1800

=108

Salesperson will make $108 in $1800 sales

Here,

tip=18%of $32

tip=(18/100)*32

=0.18*32

=$5.76

Total payment=32+5.76=$37.76

Speed=Distance/time

Here,

distance=15m

time=1sec

speed=15/1=15m/sec

Distance=Speed*time

time=15min=15*60sec=900sec

Distance travelled in 15 min=15*900=13,500m

=13500/1000 km=13.5Km

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

The answer is in the image 

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

The answer is in the image