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erma4kov [3.2K]

3 years ago

6

One person can do a certain job in twenty-one minutes, and another person can do the same job in twenty-eight minutes. How many

minutes will it take them to do the job together?
6 min
12 min
24 min

2 answers:

grigory [225]3 years ago

6 0

the correct answer is 12

MrMuchimi3 years ago

6 0

Answer: 12 min

Step-by-step explanation:

Given: Time taken by one person to do a job = 21 minutes

Time taken by another person to do a the same job = 28 minutes

If they work together then the total time taken by both of them to complete the job is given by :-

$\frac{1}{T}=\frac{1}{21}+\frac{1}{28}\\\\\Rightarrow\frac{1}{T}=\frac{4+3}{84}\\\\\Rightarrow\frac{1}{T}=\frac{7}{84}\\\\\Rightarrow\frac{1}{T}=\frac{1}{12}\\\\\Rightarrow T=12$

Hence, they will take 12 minutes to do the job together.

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A rental moving truck can haul a maximum of 7,500 pounds. Dejuan has boxes that weigh 40 pounds and boxes that weigh 75 pounds.

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WILL MARK BRAINLIEST!! PLEASE HELP ASAP.

Rudiy27

Answer:

I think this is the answer I hope this can help you

Step-by-step explanation:

1) 3 gallons=36 miles

16 gallons=?

so it will be

$36 \times 16 = 576$

$576 \div 3 = 192$

or you can do like this

1 gallons=12 miles so if 16 gallons multiply with 12 it will be 192

2)2 hours=$28.50

? =$99.75

so it will be

$99.75 \times 2 = 199.5$

$199.50 \div 28.50 = 7$

so it will be 7 hours

3) 4.5 km= 5 hours

? =60 hours

$60 \times 4.5 = 270$

$270 \div 5 = 54$

the answer will be 54 kilometer

4) $9.60=3cm

$22.40=?

$22.40 \times 3 = 67.20$

$67.20 \div 9.60 = 7$

7 cm

5) $145.50=50 miles

$552.90=?

$552.90 \times 50 =27645$

$27645 \div 145.50 = 190$

190 miles

6)$239.85=359

$1.95=?

$359 \times 1.95 = 700.05$

$700.05 \div 239.85 = 2.92$

2.92 liter

7)

220=60 hours

?=3 hours

$220 \times 3 = 660$

$660 \div 60 = 11$

11 miles

8)1 gallon= $17.50

8.2 gallon=?

$17.50 \times 8.2 = 143.50$

$143.50

9)7cm=2 minute

? =13 minute

$13 \times 7 = 91$

$91 \div 2 = 45.5$

45.5 cm

10)17=4 acres

? =244 acre

$244 \times 17 = 4148$

$4148 \div 4 = 1037$

1037 kg

11) 1= $2.85

4.4=?

$2.85 \times 4.4 = 12.54$

$12.54

12)

$2.50=5 oz

$32.50=?

$32.50 \times 5 = 162.50$

$162.50 \div 2.50 = 65$

65 oz

5 0

3 years ago