A student measures three lengths a, b and c in cm and a time t in seconds:

a = 40 ± 5
b = 30 ± 3
c = 20 ± 1
t = 1.2 ± 0.1

What is a+b
a+b+c
a/t
(a+c)/t

Calculate (1.23 ± 0.03) + pi

Question 9.4. Calculate (1.23 ± 0.03) × pi

Can you do a sample calculation of each of those please? This is for error analysis.