Answer:
Step-by-step explanation:
the current ages:
father= 32 yrs old
son=5 yrs old
-------
4(5+x) = 32+x
20+4x = 32+x
4x-x = 32–20
3x =12
x = 12/3
x = 4 years
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after the 4 years later the farther age will be 36 ( 32+4 = 36)
the son will be 9 ( 5+4= 9 years)
the x presents how the father will be after 4 times the age of the son
A=1/10, b=1/12, c=1/15 (these are the rates for each worker...)
1.)
2(1/10)+4(1/12)+t/15=1
1/5+1/3+t/15=1
(3+5+t)/15=1
3+5+t=15
8+t=15
t=7
So it would take c 7 hours to finish the job.
2.)
1/40-1/60
(3-2)/120
1/120
The drain rate is 1/60. So you will need to find t when the tank is empty, while starting at 2/3 capacity...
2/3-t/60=0
(40-t)/60=0
40-t=0
t=40
It would take 40 minutes to empty the tank when it is 2/3 full.
7x (13x^2 - 8) = 91x^3 - 56x
She can buy 3 tubes be cause 8.50 time 2 is less then 20$ but 8.50 times three is more than 20$ its 25.5
