help me on my physics homework please..?

so, someone please give your hand to me for solving these Questions.. give the steps!.

1. The quantity of charge, Q, in coulombs passing through an electrochemical cell is : Q= I * t, where I is the current in amperes and t is the time seconds. when a current of ( 0.15 ± 0.01 ) A passes through the cell for ( 120 ± 1 ) s, the total charge is Q= (0.15 A) * (120 s) =18 C. the absolute uncertainty in the total charge is..

2. The quantity of charge, Q, in coulombs passing through the cell is : Q= I * t, where I is the current in amperes and t is the time in seconds. when a current of ( 0.15 ± 0.01) A passes through the cell for (120 ± 1) s, the total charge is Q=(0.15 A) * (120 s) = 18 C . the relative uncertainty in the total charge is....

3.For an analytical technique, the relationship between the measured signal and an analyte's concentration is given by the question :

Smeas = kCA + Sreag

Calculate the absolute and relative uncertanties in the analyte's consentration if Smeas is ( 24.37 ± 0.02 ), Sreag is (0.96 ± 0.02), and k is (0.186 ± 0.003) ppm-1.

those are the questions. i had tried to answer these, but i still doubt with my answer. help me guys.. whe you answer this dont forget to give the steps ok. help me:"(