Answer:
The sequence above is a geometric sequence
For an nth in a geometric sequence

where n is the number of terms
a is the first term
r is the common ratio
From the question
a = 45
r = 15 / 45
The explicit formula for the sequence is
U(n) = 45(1/3)^n-1
Hope this helps you
Answer:
4 inches
Step-by-step explanation:
Every 25 miles the map shows 1 inch
100 miles is equal to 4 x 25 miles, thus 100 miles on the map will be 4 times longer than 1 inch => 4 inches