Byron is 3 years older than Doug. The product of their ages is 40. How old Doug? A. 10
B. 8
C. 5
D. 4

Option B is correct

Step-by-step explanation:

Doug is x years old, so Byron is x+3 years old. The product of their ages would then be x times x+3:

x(x+3) = 40

x2 + 3x = 40

x2 + 3x + 40 = 0

Now, factor the equation:

(x+8)(x-5) = 0

Then, solve for both values of x:

x+8 = 0

x = -8

x-5 = 0

x = 5

As no one can have a negative age, we simply disregard x=-8 as invalid. Therefore, Doug is 5 years old & Byron must be 5+3 - or 8 years old.

Doug is 10 years old; option A

Step-by-step explanation:

set up expressions using the information you already know:

B (byron)

D (doug)

B = D + 3

B * D = 40

you can now solve by plugging in an expression for the variable B in the second equation.  

D + 3 * D = 40

D + 3D = 40

(combine like terms)

4D = 40

(divide by 4 on both sides to isolate the variable and balance the equation)

4D/4 = 40/4

D = 10

So, the answer is A; Doug is 10 years old

step-by-step explanation:

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.

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