Answer:
Total cost=$25
Step-by-step explanation:
We can derive two expressions as follows;
Total cost for the First shipping company=Medium box charges+total additional charges
where;
Medium box charges=$20
Total additional charges=Charges per pound×number of additional pounds (n)
Total additional charges=1×n=n
replacing;
Total cost for the First shipping company=20+n....equation 1
Total cost for the second shipping company=Medium box charges+total additional charges
where;
Medium box charges=$15
Total additional charges=Charges per pound×number of additional pounds (n)
Total additional charges=2×n=2 n
replacing;
Total cost for the First shipping company=15+2 n....equation 2
Equating equation 1 and equation 2
15+2 n=20+n
2 n-n=20-15
n=5
Replace the value for n in equation 2
Total cost for the First shipping company=15+2 n....equation 2
Total cost=15+(2×5)=$25
