Question

If 2/5 ton of concrete covers 5/6 of a wall, how much concrete is required to cover the entire wall

Answer 1

Note¹: One integer is 6/6 of the wall
Note²: Make the rule of three simple

ton __ Coverage 
$\frac{2}{5}$ --------------- $\frac{5}{6}$
y --------------- $\frac{6}{6}$

Solving: (directly proportional)

$\frac{ \frac{2}{5} }{y}= \frac{ \frac{5}{6} }{ \frac{6}{6} }$

Product of extremes equals product of means

$\frac{5}{6} *y = \frac{2}{5} * \frac{6}{6}$

$\frac{5y}{6} = \frac{12}{30}$

Product of extremes equals product of means

$5y*30 = 6*12$
$150y = 72$
$y = \frac{72}{150} \frac{\div6}{\div6} \to \boxed{\boxed{y = \frac{12}{25} }}\end{array}}\qquad\quad\checkmark$

Answer:
$\frac{12}{25}\:\textbf{ton\:of\:concrete}$ or 0.48 ton of concrete