Answer:
She increased 80% the practise time
Step-by-step explanation:
The question is incomplete, the following is missing:
<em>by how much did she increase the time she practised each day?
</em>
From Monday to Wednesday she increased 90 - 50 = 40 minutes the practise time.
To compute the increment as a percentage use: increment/reference *100
In this case, that is: 40/50*100 = 80%, where 50 minutes is taken as a reference.
Y=-5x-7. I'm almost certain but you never know
I'm assuming all of (x^2+9) is in the denominator. If that assumption is correct, then,
One possible answer is 
Another possible answer is 
There are many ways to do this. The idea is that when we have f( g(x) ), we basically replace every x in f(x) with g(x)
So in the first example above, we would have

In that third step, g(x) was replaced with x^2+9 since g(x) = x^2+9.
Similar steps will happen with the second example as well (when g(x) = x^2)
Total work amount
6 men * 14 days
84 men days
If it is done within 21 days, need x men
84 men days = x men * 21 days
x = 84/21 men
x = 4 men
19% of 546 is 103.7 approximately $104 so the answer is 19%