What is the sign of 3xy when x> 0 and y< 0?

Let see.

Numbers which are bigger than 0 are defined as positive numbers and have a prefix of + (plus).

Numbers which are smaller than 0 are defined as negative numbers and have a prefix of - (minus).

Let say number a is equal to the expression,

Since y is negative we can change its prefix to -,

Any number (in this case 3x) multiplied by negative number will produce a negative number.

Therefore the sign or prefix of number a will be -.

Hope this helps.

r3t40