Question 952617
a=one side=18cm; b and c are other sides
b-c=4.6cm
b=4.6cm+c 
p=a+b+c
48cm=18cm+b+c Subtract 18cm from each side
30cm=b+c Substitute for b
30cm=(4.6cm+c)+c Subtract 4.6cm from each side
25.4cm=2c Divide each side by 2.
12.7cm=c ANSWER 1: One of the other sides is 12.7cm.
b=4.6cm+c=4.6cm+12.7cm=17.3cm ANSWER 2: The other side is 17.3 cm.
CHECK:
a+b+c=48cm
18cm+12.7cm+17.3cm=48cm
48cm=48cm