Value of a resistor?

[gm_bowen]

Two resistors, when connected in parallel have an equivalent resistance of 15 ohms. If one of the resistors is 60 ohms what is the value of the other?

Question from 2330.

Can't apply 1/Rt = 1/R1 + 1/R2 + 1/R3

Was suggested use product over sum method, but not been able to calculate it?

Help appreciated.

 

[Grae79]

red band - black band - black band

 

[randyrat]

20 ohms

product over sum:

total res = product/sum

15 = 60 times R divided by 60 plus R

therefore

15 times (60 plus R) = 60 times R

therefore

900 plus 15 times R = 60 times R

therefore

900 = 45 times R

therefore R = 900 divided by 45 (equals 20 Ohms)

Easy
Randyrat