Here the answer is 19/35
Step-by-step explanation:

We will apply BODMAS rule
In this rule multiplication comes before add and subtraction
= 
= 
= 
= 
= 
= 
When i converted it 4.5 meters is 450 centimeters
You solve this by plugging one equation into the other. Usually you have to rewrite one equation to make this work. In this case I choose to rewrite y-4x=0 as y=4x.
After plugging it into the second, you get:
3x + 6*4x = 9 => 27x = 9 => x=1/3
Putting this solution back into y=4x gives us y=4/3
If he plays 3 matches a week for 9 weeks, you have to multiply 3&9.
3*9=27
Daniel will have played 27 tennis matches by the end of the 9 weeks.
Hope this helps:)