Answer:
21
Step-by-step explanation:
It is 21 since 21 = 3 * 7.
The other 3 numbers are prime.
Answer:
120
100+5w=m (m is his money after saving up)
Answer:

Step-by-step explanation:
<u>Directly Proportion</u>
It's said that y varies directly proportional as x, if:

Where k is a constant of proportionality.
We know that y=7 when x=1/2.
Using the above condition, we can find the value of k:

Solving for k:
k=14
Thus, the equation is:

x is a variable which in math means an unknown number, since 2+2=4 the answer (If your trying to find what x is) would be x=4.
The solution set is 
Explanation:
The given equation is 
To determine the solution set of the equation, let us solve the equation.
Adding both sides of the equation by 3, we have,

Taking square root on both sides of the equation, we get,


Thus, the solution of the equation is 
The solution set of the equation is the set which contains all the solutions of the equations.
Thus, writing the solutions of the equation using set notation, we have,

Thus, the solution set is 