95
92
To find the number of ducks in the zoo, we use the given information: There are 160 heads and 450 legs. Let the number of ducks be \(d\) and the number of rabbits be \(r\). Since each duck and rabbit has one head, we have the equation:
\(d + r = 160\)
Each duck has 2 legs and each rabbit has 4 legs. Thus, the second equation is:
\(2d + 4r = 450\)
We can simplify the second equation by dividing it by 2:
\(d + 2r = 225\)
Now, we have the system of equations:
\(1. \quad d + r = 160\)
\(2. \quad d + 2r = 225\)
Subtract equation 1 from equation 2:
\((d + 2r) - (d + r) = 225 - 160\)
\(r = 65\)
Substitute \(r = 65\) back into equation 1:
\(d + 65 = 160\)
\(d = 160 - 65\)
\(d = 95\)
Therefore, the number of ducks in the zoo is 95.
The largest $ n \in \mathbb{N} $ such that $ 3^n $ divides 50! is:
Identify the part of the sentence that contains a grammatical error:
Each of the boys have submitted their assignment on time.
Rearrange the following parts to form a meaningful and grammatically correct sentence:
P. a healthy diet and regular exercise
Q. are important habits
R. that help maintain good physical and mental health
S. especially in today's busy world