4. 13/30 + 14/20 =

Find a common denominator for 30 and 20, which is 60.

Convert the fractions: (13*2)/(30*2) + (14*3)/(20*3) = 26/60 + 42/60.

Add the numerators: (26 + 42) / 60 = 68/60. Simplify to 17/15.