Question

62x + 82x + 92 + 61x = 731

Answer 1

$62x + 82x + 92 + 61x = 731 \\ \\ = \geqslant 62x + 82x + 61x = 731 - 92 \\ \\ = \geqslant 144x + 61x = 639 \\ \\ = \geqslant 205x = 639 \\ \\ = \geqslant x = \frac{639}{205} = 3.11$

Answer 2

Refer the attachment......

IT IS DoNE BY ADDICTION..