Voltie
— they/them
Posted 7 years ago ( 2018/05/3 18:59:22 )
I set up the problem the same way as @Littlewhitedragonlet: did
(120(5) + 180x)/(5+x) = 170
(600 + 180x)/(5+x) = 170
600 + 180x = 170(5+x)
600 + 180x = 850 + 170x
180x - 170x = 850 - 600
10x = 250
x = 25 km for the second part of the journey
So the whole journey was 25 + 5 = 30 km.
@Shadami: is right :)
Voltie
— they/them
Posted 7 years ago ( 2018/05/3 19:33:15 )
@Dipper: Well here's problem 2. I'm actually not bothering with the first one, all that counting looks way too tedious xD
4 large + 2 small takes the same amount of time as 2 large and 6 small
4L + 2S = 2L + 6S
4L - 2L = 6S - 2S
2L = 4S
L = 2S (A large brush can paint twice as much as a small. I'm gonna sub 2S in for L everywhere and convert all my large brushes to small so I have fewer variables)
4L + 2S = 10S
2L + 6S = 10S (we already knew it would be the same)
8L + 8S = 24S
It takes two hours to paint the garden with 10 small brushes. The more brushes we have, the less time it should take, so brushes and time have an inverse relationship. That means when I multiply or divide my brushes, I should do the opposite to my time.
10 brushes takes 120 minutes
10/10 brushes takes 120*10 min
1 brush takes 1200 min
1*24 brushes takes 1200/24 min
24 brushes takes 50 minutes to paint the whole garden
We wanted only half the garden though, so it would take half the time, or 25 minutes.