Miko drew this scale drawing of two famous landmarks miko used a scale of 1 in. 400 ft. use equations to find the actual heights of the two structures. what is the approximate difference in their heights?

The complete question in the attached figure N 1

we have that
Miko used a scale of 1 in. 400 ft
that means 
1 in in the drawing is --------------> 400 ft in the actual
[scale]=[drawing]/[actual]----------> [actual]=[drawing]/[scale]
[scale]=1/400
[actual]=[drawing]/[scale]------> [actual]=[drawing]/[1/400]
[actual]=400*[drawing]----------> this is the equation to find the actual height 

so
the height of the Space needle in the drawing is approximate 1.5 in
the height of the Eiffel tower in the drawing is approximate 2.75 in

see the attached figure N 2

the height of the Space needle in the actual is approximate
[actual]=400*[drawing]
[actual]=400*1.5----> 600 ft

the height of the Eiffel tower in the actual is approximate
[actual]=400*[drawing]
[actual]=400*2.75-----> 1100 ft

the approximate difference in their heights is [1100-600]=500 ft

the answer is
the approximate difference in their heights is 500 ft

What exactly is your question?