Materials 4405

Two trucks were supposed to load the building materials in 10 days. After 6 days of work, the first car broke down, and the second one carried building materials for another 9 days. How many days would the first and second cars take the building materials?

Correct answer:

a =  18 d
b =  22.5 d

Step-by-step explanation:

$$\begin{gathered} 1/a+1/b=1/10 \\ 6/a+(6+9)/b=1 \\ a=18=18\text{d} \end{gathered}$$

$b=1/(1/10-1/a)=1/(1/10-1/18)=22.5\text{d}$

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