How should the resultant of a + b look?

Which changes would result in a decrease in the gravitational force btween two objects? check all that apply

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

If jason ii needs 15 kw of power at 300 volts to operate, what amperage of current must flow through the cable?