Answer:
9:7
Explanation:
Convert all the numbers to either decimal or fraction. The operation becomes simple.
Simplifying after converting to decimal
Convert 3 1/2 to decimal 3 1/2 = 3 + 1/2
1/2 = 0.5
3 + 1/2 = 3 + 0.5 = 3.4
Ratio 4.5:3.5 = 4.5/3.5
Divide by 5 to give

Multiply both numerator and denominator by 10
0.9 x 10 = 9
0.7 x 10 = 7
So the ratio becomes 9/7 = 9:7
Simplifying after converting to fraction
4.5 = 4 + 0.5
0.5 = 1/2
5.5 = 4 + 1/2 = 4 1/2
Convert to mixed fraction:
4 1/2 = (4 x 2 + 1)/2 = 9/2
Convert 3 1/2 to fraction
3 1/2 = (3 x 2 + 1)/2 = 7/2
So 4.5 : 3 1/2 = 9/2 : 7/2
Multiplying by 2 we get the same answer: 9:7
Choose whichever approach you feel comfortable with