Explicație pas cu pas:
[tex] \frac{5 \times 4 \times n}{4} + \frac{n \times 4 \times 3}{4} = 7 \\ \frac{20n}{4} + \frac{12n}{4} = \frac{28}{4} \\ \frac{32n}{4} = \frac{28}{4} \\ 8n = 7 \\ n = \frac{7}{8} [/tex]
