Answer:
3
Explanation:
You want to know the value of the short side of the smaller of two similar triangles when the side ratio in the larger is 5 : 7.5, and the longer side in the smaller triangle is 4.5.
Proportional
Corresponding side lengths are proportional in these similar triangles:
x/4.5 = 5/7.5
x = 5(4.5/7.5) = 5(3/5)
x = 3
The length of x is 3.