0
$\begingroup$

Hello i got stuck with such kind of questions

say there is line divided into 3 parts

first part is 2/5 of total. Second part is 3/8 of total and third part is unknown. What is the total length when first part is 4meters greater as the second one.

my problem is writing formulas for such kind of questions.

Any help is appreciated

2 Answers 2

0

Assume the total length of the line is $x$ and the length of the unknown third part is $y$. Then you know that $\frac{2}{5}x + \frac{3}{8}x + y = x$ (i.e. the first two parts plus the third equals the length of the whole line) and from the second condition you know that $\frac{2}{5}x = \frac{3}{8} x + 4$ (the second part is 4m longer than the second one).

You can easily solve the second equation to obtain $x=160$[m]. Plug this into the first equation to find $y=36$[m].

  • 0
    i come with the first part of equation . hovewer i we been stuck with the '4meters 'part of the equation. thanks – 2017-01-11
3

Let $L$ be the total length (your final answer).

"First part is $4$ meters greater than the second part" can be written as $$\frac{2}{5}L - \frac{3}{8} L = 4 \text{ meters}.$$ Solve for $L$.

  • 0
    im glad for each answer thanks – 2017-01-11