6 watermelons, because each watermelon is 2 kg
Sorry, my answer was wrong. I can't delete it so as not confuse anybody i changed it to this.


keep in mind, that "t" is the time when the train at A station, left towards B station
they met, at some time "t", and by the time that happened, train from A
which started 3 hours earlier, had already covered "d" distance,
whatever that is
and the train coming from B, covered, 600-d, or the difference
Step-by-step explanation:
the answer is c: 2..............
A = 8i + 6j
b = 4i + 5j
ab = (8i + 6j)(4i + 5j)
ab = 8i(4i + 5j) + 6j(4i + 5j)
ab = 8i(4i) + 8i(5j) + 6j(4i) + 6j(5j)
ab = 32i² + 40ij + 24ij + 30j²
ab = 32i² + 64ij + 30j²
ab = <32, 30>
The answer is D.