series combination of 2 resistors, 8.80 Ω and 4.12 Ω, is connected to a 9.00 V battery. Calc equivalent resistance of circuitAnswer units Ω?

suppose you have n resistors having resistance R1, R2,.. .. Rn.

If they are arranged in series, they can be replaced by single resistor (Req).

Req = R1 + R2 + ... + Rn

if they all are arranged in parallel, they can be replace by single resistor (Req)

1/Req = 1/R1 + 1/R2 + ... + 1/Rn

in your case, equivalent resistance will be 8.8 Ω + 4.12 Ω = 12.92 Ω

if they were connected in parallel, the equivalent resistance (Req) would have been given by

1/Req = (1/ 8.8 Ω) + (1/ 4.13 Ω)

= (8.8 + 4.13)/(8.8 x 4.13) Ω^-1

Req = (8.8 x 4.13)/(8.8 + 4.13) Ω

12.92

Resistors in series add, and the applied voltage is irrelevant in calculating equivalent resistance.

this is really basic stuff, and should have been covered in your book or lecture or other class material.