I believe 1:45
He started work at 7:15 just add 6 hours to 7 and half-hour to 15 minutes
Imagine what x is quantity of stools. So
3x+120=4x
x=120
120 stools in cafeteria
120 chairs in cafeteria
120+120=240
There 240 people can sit in this cafeteria
Assuming compount interest format

for compounded per 1 year
A=future amount
P=present amount
r=rate in decimal
t=time in years
given
P=270
r=5%=0.05
the equaton is

or

for any year, 2009, is year 0, so if you wanted to input the year then

would be for t=what year it was
A.

b. 2009 to 2020
2020-2009=11 years
t=11

f(11)=461.792
about 462 cranes
A.

B. about 462
7x+3y=-1
x+y=-3
8x+4y=-4
2x+y=-1
y=-1-2x
x+y=-3
x-1-2x=-3
-x=-2
x=2
y=-1-2*2=-1-4=-5