[10.15] Terrell and Mindi are organizing a neighborhood skateboarding competition. They need to build two mini ramps. Terrell can build the ramps in 15 hours. Mindi can build the ramps in 20 hours. Which shows the equation and solution for the time it will it take Terrell and Mindi to build the ramps if they work together? Round your answer to the nearest hour, if necessary.

Question

anonymous · Answer

2 equals the quantity 2 over 15 plus 2 over 20, end quantity, times t; 9 hours 

 1 equals the quantity 2 over 15 plus 2 over 20, end quantity, times t; 4 hours 

 2 equals the quantity 15 over 2 plus 20 over 2, end quantity, times t; 4 hours 

 1 equals the quantity 15 over 2 plus 20 over 2, end quantity, times t; 9 hours

anonymous · Answer

I know it is a or c? Right?

amistre64 · Answer

dunno yet, the options are rather odd looking.

anonymous · Answer

hmm...I wuill see if I CAN MAKE IT BETTER. :)

amistre64 · Answer

Terrell can build the ramps in 15 hours. 

15 hours = 1 ramp; so  1/15 of a ramp in 1 hour

Mindi can build the ramps in 20 hours.

20 hours = 1 ramp; so, 1/20 of a ramp in 1 hour

the time it will it take Terrell and Mindi to build the ramps if they work together

$$h(\frac{1}{15}+\frac{1}{20})=2 ramps$$

amistre64 · Answer

$$\large h = \frac{2}{(\frac{1}{15}+\frac1{20})}$$

amistre64 · Answer

shouldnt be a 2, i read it as 1 ramp per hours; should be 1 job

anonymous · Answer

Oh, okay, hmm....

amistre64 · Answer

so, what is 1/(1/15+1/20) ??

anonymous · Answer

attachment

anonymous · Answer

attachment

amistre64 · Answer

oh, i already wrote up one of those

$$h(\frac{1}{15}+\frac{1}{20})=1$$

anonymous · Answer

Oh, hey sorry, I think you mean2 instead of 1, right? because everything has a two on it. :)

amistre64 · Answer

if we multiply both sides by 2 we get one of the options

amistre64 · Answer

$$h(\frac{2}{15}+\frac{2}{20})=2$$

anonymous · Answer

yeah, 1 of them has a t(2/15=2/20)=1

anonymous · Answer

and a 2. :)

amistre64 · Answer

i believe option A matches up fine

anonymous · Answer

OK, I think you are right! LOL! Thx for your help! That is all I need for now. :)

amistre64 · Answer

god luck ;)

anonymous · Answer

Byee, I will close the question soon. :D

amistre64 · Answer

err, good luck even lol

anonymous · Answer

sorry, was taking a bath, thanks so much for your good wishes!