The total mass of a box and a watermelon was 7 kg 34 g. When some strawberries were added into the box, the total mass became 8600 g. The watermelon was 3 times as heavy as all the strawberries added. Find the mass of the box, in grams.
7 kg 34 g means 7000 g plus 34 g — the 34 fills the ones and
tens columns, not the hundreds. So the starting mass is 7034 g, not 7340 g.
Strawberries = 8600 − 7034 = 1566 g.
Box = 7034 − 4698 = 2336 g.
is the mass of the box.
The trap: reading 7 kg 34 g as 7340 g. It is 7000 + 34 = 7034 g — the 34 fills the ones and tens columns, not the hundreds.